A three-year-old girl is among 21 injured after a group of men attacked a woman with pepper spray in an alleged suitcase robbery at Heathrow Airport.

One man was arrested by armed police as 16 victims, including the toddler, were treated at the scene and five more were rushed to hospital.

Police, ambulance and fire engines swooped on the multi-storey car park in Terminal 3 just after 8am today, sparking hours of travel chaos for holidaymakers.

Scotland Yard is investigating the alleged robbery in which a group of four men attempted to steal a woman’s luggage shortly after her flight landed at Heathrow.

It’s understood they sprayed the substance at her in a car park lift, affecting other passengers inside and in the surrounding area.

A 31-year-old man has been arrested on suspicion of assault, but the other suspects are believed to have fled the scene.

The Met initially characterised the incident as an argument involving two groups of people known to each other that escalated into a fight, but study of CCTV footage and interviews with witnesses cast new light on events.

In an update on Sunday afternoon, Commander Peter Stevens said: ‘At this stage, it’s understood that a woman was robbed of her suitcase by a group of four men, who sprayed a substance believed to be pepper spray in her direction.

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One man was arrested by armed police at Heathrow in connection with the pepper spray attack

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Elizabeth Line passengers queuing to exit the Heathrow T2/3 station amid overcrowding following the incident

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The incident caused widespread travel disruption, with further chaos expected throughout the day

‘This occurred within a car park lift, with those in the lift and surrounding area affected by the spray.

‘Our officers are working to determine the full circumstances around what happened but we do believe this to be an isolated incident with those directly involved known to each other.

‘We appreciate that this has been a concerning incident and I commend the actions of the emergency services and members of staff at Heathrow Airport.’

The ordeal, which is not being treated as terrorism, sparked major travel disruption as flights were delayed or cancelled, public transport was suspended and drivers were not allowed to leave their cars.

Underground and Elizabeth Lines connected to the airport were brought to a halt, bus drivers were trapped inside the station, and the short stay car park entrance was blocked, causing a major backlog of vehicles unable to leave the vicinity.

The delays were sparked as armed police urgently searched for suspects before arresting one man on suspicion of assault.

One woman said she wasted seven hours travelling and waiting around at the airport after her flight was cancelled.

‘Absolute chaos at Heathrow this morning – seven hours wasted and trip cancelled after I missed my flight,’ she wrote on X.

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Armed police at the scene as they checked cars and looked for suspects

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Traffic was brought to a halt at the busy London airport after a major incident was declared

Heathrow staff handed out bottled water to frustrated passengers waiting for buses from Terminal 3 this afternoon.

One family, who did not wish to be named, said they had been stood at the bus stop for three hours for a shuttle to the long-stay car park after their flight.

Hudaifa Yunis, 35, who was picking family up from the airport, said: ‘It was chaos. Everyone was running around and passengers were bumping into each other. It caused massive congestion.’

Another traveller said around 300 people were waiting to get into lifts inside the terminal.

Kate, who was held up at Heathrow today, said: ‘No one [was] there to help or guide.’

Tense footage posted on social media showed armed police searching the airport car park, leaving worried drivers stuck in their vehicles.

One trapped driver wrote on X: ‘Who knows what’s happening at Heathrow T3, stuck here for nearly an hour and armed police searching every car about.’

Another man sat outside the airport said: ‘It’s chaos inside the terminal. It doesn’t seem like anyone knows what’s going on in there.

‘We tried to get up to Terminal 2, but we had to queue up and they told us to go back after 20 minutes of waiting. Nobody knows what’s going on over there.’

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Traffic is brought to a standstill outside Heathrow Airport today after the incident

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Traffic at a standstill heading towards Heathrow after the incident this morning

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Heathrow-bound travellers wait to board the Heathrow Express after long delays in London today

Fin Fraser, who travelled into Heathrow from the US on Sunday, said he witnessed ‘armed police running around and checking people’s vehicles’ as he was trying to leave the car park.

‘When they came to ours, they knocked on our window and told us to wind it down and then they looked inside the car,’ he told the BBC.

Meanwhile, Tom Bate said he was waiting for a lift in Terminal 3’s car park when he saw ‘young men dressed in black darting through the crowd’.

‘As soon as they left people started coughing, and then I started to cough,’ he said. ‘I felt a burning at the back of my throat.’

Bate said he initially feared the worst as a large group of officers carrying guns ran past him shouting.

‘It was absolutely terrifying and I 100 per cent believed that I was in a terrorist attack for a few moments,’ he said.

An officer pointed a gun at a man and ordered him to the ground to arrest him, he added.

‘Although the officers were very professional, even they were not in control at that moment while they were trying to figure out what was actually going on. They genuinely didn’t know what they were dealing with,’ he told The Times.

‘And that was a slightly eerie moment, evocative of disaster movies where you realise no one is actually in control.

‘I wound down the window, called them over and said “Are you looking for three young men?” They said “Yes”. I pointed them towards the staircase and said “They went that way”.

‘That’s when I connected the two, that they may have had something to do with the weird coughing.’

Police said victims of the attack are believed to have been assaulted with a form of pepper spray by a group of men.

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Queues at Heathrow this afternoon after chaos was caused by the incident

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Traffic unable to move at Heathrow after the major incident this morning

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A man is arrested at Heathrow Airport today following an incident understood to involve pepper spray

A Met Police spokesperson said: ‘Police are in attendance at Heathrow Airport while we investigate the circumstances around the assault of a number of people this morning.

‘Officers were called at 08:11hrs to a multi-storey car park at Terminal 3 following reports of multiple people being assaulted. A number of people were sprayed with what is believed to be a form of pepper spray by a group of men who then left the scene.

‘Armed response officers attended and arrested one man on suspicion of assault. He remains in custody and enquiries continue to trace further suspects.’

Police added that the victims were taken to hospital, and their injuries are not believed to be life-changing or life-threatening.

Commander Stevens previously said: ‘At this stage, we believe the incident involved a group of people known to each other, with an argument escalating and resulting in a number of people being injured.

‘Our officers responded quickly and there will be an increased police presence at Heathrow airport throughout the morning to continue inquiries and ensure the safety of those in the area.

‘We are not treating this incident as terrorism. I understand the public’s concerns, and would like to thank those in the area for their co-operation this morning.’

The London Ambulance Service said 21 patients were cared for at the scene, before five were transported to hospital.

A spokesperson said: ‘We sent a number of resources to the scene, and cared for 21 patients. Five patients were taken to hospital. The ambulance service was stood down from the scene at 10.58am.’

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Emergency vehicles outside Heathrow Terminal 3 after a man was arrested on suspicion of assault

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Fire engines arrive at the airport this morning surrounded by traffic chaos caused by the incident

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One man sat outside the airport said: ‘It’s chaos inside the terminal. It doesn’t seem like anyone knows what’s going on in there’

A Heathrow Airport spokesman said: ‘The incident at the multi-storey car park in Terminal 3 has now been contained by the Metropolitan Police.

‘Congestion remains on surrounding roads following the incident which we are working hard to resolve as quickly as possible and we are advising passengers to use public transport.

‘There will be an increased police presence at Heathrow Airport to maintain the safety of people in the area and reassure the public.’

A London Fire Brigade spokesman said this morning: ‘We were called at 8.14am today to assist emergency service colleagues at an incident near Terminal 3 at Heathrow Airport. Firefighters remain at the scene.’

National Rail has confirmed train lines have reopened, but disruption is expected to continue throughout the day.

A spokesperson said: ‘Lines have reopened allowing trains to be able to call at Heathrow Airport following the emergency services dealing with an incident at the Airport.

‘Although lines have now reopened, disruption is expected to continue whilst services return to normal, delays of up to 10 minutes and cancellations can be expected until 11:45.’