Passengers queued outside London City Airport after it was evacuated Friday.

Story highlights

Incident left 27 people complaining of breathing difficulties

The 25-year-old was released on bail until a date in November

CNN  — 

Police in London have arrested a man on suspicion of releasing a chemical substance at one of the city’s airports, following an incident which led to the evacuation of the terminal Friday.

The Metropolitan Police said that a 25-year-old man had been arrested Saturday following the episode at London City Airport, which left 27 people complaining of breathing difficulties and feeling unwell.

The man was arrested on suspicion of using a noxious substance to cause serious damage, an offense under anti-terror laws.

He was not charged, but released on bail until a date in late November. Police said that the case is being investigated by aviation investigators, rather than counter-terrorism police at this point.

Passengers wore emergency blankets to keep warm outside the terminal.

The airport was evacuated Friday after a number of passengers reported feeling unwell, police said.

Firefighters were alerted to the incident at about 4 p.m. (11 a.m. ET), officials said. The airport was reopened more than three hours later after the building was declared safe.

Authorities believe the incident might have been caused by a CS gas spray – a type of tear gas – but are still investigating. “Whilst the cause of the incident has not yet been confirmed, officers are investigating if it was the result of an accidental discharge of this canister,” a statement says.

The city’s ambulance service said it had treated 27 patients at the scene for difficulty breathing. Two were taken to the hospital, the service said.

Alistair Snowie, who spoke to CNN on the phone from a medical tent where he was being treated, said he was waiting in line to check in for his flight home to Stirling, Scotland, when everyone started coughing.

“It all happened very quickly,” he said. “The alarm didn’t go off at first, but we all just ran. Nobody knew what was going on.”

London City Airport focuses on business travelers heading to destinations in the UK, Europe and the United States. It’s in east London.

London City Airport is the closest airport to central London.

Far smaller than Heathrow and Gatwick, the major airports in London, the airport serves more than 40 destinations, according to its Facebook page.

CNN’s Claudia Rebaza, Catherine E. Shoichet and David Williams contributed to this report.