At least two people have been hospitalized and 26 were being treated by paramedics at London City Airport Friday following "reports of a chemical incident."

"Around 500 members of the public and staff were evacuated and London Ambulance Service crews treated a number of patients for difficulty breathing," the London Fire Brigade said in a statement.

"Two complete sweeps of the Airport building were carried out jointly by firefighters and police officers both wearing protective equipment," it added. "No elevated readings were found and the building was ventilated, searched and declared safe."

The London Ambulance Service said its hazardous area response team was at the scene.

The airport said passengers were told to leave the terminal Friday afternoon because a fire alarm was sounding. Departing flights were suspended, and several incoming flights diverted to other airports.

The Metropolitan Police force said officers were called to the airport just after 4 p.m. local time "following reports of passengers being taken unwell."

City Airport, in east London's docklands, is the smallest of the British capital's international airports.

The Associated Press contributed to this report.