Incident at Heathrow Airport that saw terminal evacuated was caused by ‘mass HYSTERIA’, sources say: Passenger panic leaves more than 20 people needing medical treatment amid fears of chemical leak

An evacuation of a Heathrow Airport terminal over a mystery chemical incident which left 21 people needing medical treatment despite ‘no trace of any adverse substance’ was caused by ‘mass hysteria’.

A ‘possible hazardous materials incident’ saw Terminal 4 shut for around three hours shortly after 5pm on Monday, forcing crowds of people to gather outside while ambulances and fire crews rushed to the scene.

Twenty-one people were taken ill at the airport, while one person was taken to hospital, the Metropolitan Police said. No one was in a life threatening condition.

However, police confirmed that ‘no trace of any adverse substance was found’ at the airport, while emergency services stood down their response at around 8:30pm.

‘Around twenty people reported an injury. None were deemed to be life-threatening or life-changing. Enquiries are ongoing,’ a spokesperson for the police said.  

The incident was a ‘mass hysteria’ type event, with no hazardous materials found, a Metropolitan Police source told the BBC. 

They added that incident could have ‘snowballed’. 

The terminal was declared ‘safe to reopen’ shortly after 8pm. 

A Heathrow Airport spokesperson said: ‘Emergency services have confirmed Terminal 4 is safe to reopen and we are doing everything we can to ensure all flights to depart as planned today.

‘We are very sorry for the disruption caused, the safety and security of our passengers and colleagues is our number one priority. 

‘We encourage passengers to check with their airline for the latest information about their flight this evening and our colleagues will be on hand into the night to assist.’

The London Ambulance Service said: ‘We were called at 4.50pm to Terminal 4 at Heathrow airport. We sent ambulance crews, our cycle response unit, an incident response officer, and our hazardous area response team (HART). We treated 21 patients before taking one to hospital.’ 

Earlier, the airport had said that firefighters were responding to a ‘possible hazardous materials incident’.

‘Specialist crews have been deployed to carry out an assessment of the scene, and Terminal 4 has been evacuated as a precaution whilst firefighters respond,’ they added.

Those evacuated were given bottles of water by airport staff while foil blankets were handed out to keep people warm. 

Emergency crews were seen putting on protective white suits before entering the terminal. 

Harry Smith, 22, told the Telegraph he was checking in for a Qatar Airways flight to Vietnam when the terminal was evacuated.

‘I was escorted out of the check-in part of the terminal.

‘We saw people with hazmat suits and masks.

Other witnesses reported seeing privacy screens being put up as passengers were evacuated around 150 metres from the terminal. 

All other terminals were operating as normal while terminal 4 was closed.

Heathrow is the UK’s busiest airport. 

In March, Heathrow Airport was shut after a devastating electrical fire which sparked worldwide travel chaos and days of disruption for hundreds of thousands.

It was forced to close after its main electrical substation exploded and set alight less than two miles away in the west London suburb of Hayes.  

The closure impacted 270,000 journeys and was caused by ‘an unprecedented set of circumstances’, Heathrow chairman Lord Deighton said.

This is a breaking news story. More to follow.