Firefighters and ambulances were rushed to the scene after some 50 people at one terminal complained of eye irritation and breathing difficulties.
Hundreds of passengers at Hamburg airport were evacuated by German firefighters after an unidentified hazardous substance possibly released via the air-conditioning system caused various injuries to more than 50 persons.
As The Washington Post reported, police said there was "no evidence" that this event could be related to a terrorist attack. The fire service said what appeared to be a pepper-spray canister had been recovered. According to Euronews, which cited local media, the problem was reportedly caused by the air conditioning system.
Evacuees who were uninjured had to wait outside in freezing temperatures. Flights were halted at 12.20pm due to the fire brigade taking over the terminal building, says the Daily Mail.
The airport in Germany's third largest city was temporarily shut down and evacuated early Sunday afternoon. They were allowed back in shortly after.
Hamburg is Germany's fifth-biggest airport, handling 16 million passengers a year.