London City Airport, on the outskirts of the British capital, was evacuated around 4 p.m. local time after what first responders described as a "chemical incident." Twenty-six people have been treated and two have been hospitalized for having trouble breathing.
Five hundred people were evacuated.
"We are now all standing on the tarmac under the wing of the airplane because it has started to rain," 35-year-old passenger Chris Daly, who was amongst those evacuated, told the BBC.
"I can see some planes circling in the sky but nothing else has landed," said Daly. "No one has really told us anything. We saw some fire crew going inside to do a sweep."
This story is breaking and will be updated.