© Ruptly
London police said they arrested a 25-year-old man on Saturday. He was suspected of using a chemical substance to cause serious damage, an offence under the Anti-terrorism, Crime and Security Act.
He was arrested at his home in east London, according to the Independent. He has since been bailed.
Some 500 people were forced to leave the airport building on Friday with at least 30 flights canceled.
London Ambulance said it treated 26 people at the airport and two were taken to hospital.
The site was evacuated after a fire alarm went off in the terminal building. Passengers and airport staff were left on the tarmac as three fire engines responded to the alarm.
Protest against your government and they attack you with CS gas but in this instance we have to have medics and close down the airport for several hours