BERLIN - German firefighters on Sunday evacuated hundreds of passengers at Hamburg Airport after 50 people were injured by an unknown toxin that likely spread through the airport’s air conditioning system.

All flights were halted for several hours due to the evacuation, airport spokeswoman Karen Stein said.

“We have cancelled all flight at least until 2 p.m. (1300GMT) and most parts of the airport have been evacuated,” she said.

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More than 50 people complained about breathing problems and burning eyes and firefighters were examining them to find out whether they had to be taken to the hospital, the German news agency dpa reported.

Those who were evacuated from the airport had to wait outside the terminals in freezing temperatures.

Firefighters designated special areas outside the airport building where physicians were examining those injured by the unknown toxin.