London fire brigade said about 500 people had been evacuated from the airport's terminal.
Hundreds of passengers were evacuated from the terminal building at London City airport today amid what the fire brigade called reports of a chemical incident.
"Terminal has been evacuated due to fire alarm. We are looking into the cause," the airport said on Twitter.
London fire brigade said about 500 people had been evacuated from the airport's terminal.
"Three fire engines and a range of specialist appliances have been called to reports of a chemical incident at London City Airport this afternoon," it said in a statement.
A spokeswoman for London's Metropolitan Police said officers had been called to the airport at around 1500 GMT to reports of several passengers having been taken unwell. "The cause is not known," she added.
The airport, a few miles east of the Canary Wharf financial district, mostly serves short-haul, European destinations.
© Thomson Reuters 2016