Paramedics watch passengers re-entering the terminal building at the Hamburg Airport on Sunday. (Fabian Bimmer/Reuters)

German officials on Sunday evacuated hundreds of people from Hamburg Airport and briefly closed the facility after dozens of passengers were affected by a substance that authorities said was probably pepper spray disseminated through the air-conditioning system.

Maik Lewerenz, spokesman for the federal police in the northern German city, said that 68 people had experienced eye irritation and breathing difficulties.

Rene Schönhardt, spokesman for the Hamburg police, said there was “no evidence” that the incident was a terrorist attack. Instead, he said, the injuries most likely stemmed from a cartridge containing pepper spray that was found in a bin provided for travelers to dispose of liquids before boarding.

“Nothing else has been found,” Schönhardt said. “The fire department didn’t detect any dangerous substances.”

Werner Nölken, spokesman for the Hamburg fire department, said, “We are not assuming a terrorist attack.” The current assumption, he said, was that “some clown, for whatever reason” released pepper spray into an air-conditioning vent, causing the substance to spread.

The cartridge found in the bin was only the size of a lipstick, he said, so it would not have been possible to injure so many people without the air-conditioning system diffusing the gas.

Airport officials said in a statement that an investigation was underway to determine how the substance got into the system.

Passengers and staff in a security luggage-check area began complaining about a bad smell, burning eyes and nausea around 11 a.m., and many were coughing. More than a dozen flights were canceled, and by 12.30 p.m., all the airport terminals had been evacuated.

Flights resumed about 2 p.m., and the terminals were reopened.

Although authorities were quick to rule out a terrorist agenda, the incident shows how easy it is to disrupt everyday life at a time of rising fear of such attacks in Germany. The country has been on edge since the Dec. 19 attack on a Christmas market in Berlin that left 12 people dead and dozens injured.