Munich Airport was forced to cancel around 130 flights on Tuesday after police halted check-in and evacuated the building to search for a passenger who mistakenly went through an emergency exit.
Police said they had to order all people out of the airport, including passengers who had already passed through security, to ensure no dangerous items had been left behind.
The missing passenger, a Spanish man who opened an emergency door in terminal 2, was later found in terminal 1. Check-in resumed after a four-hour shutdown which would lead to significant delays for the rest of the day, the airport said.
The airport handed out water bottles to waiting passengers on a hot, sunny day in Munich.
Person at Munich airport detained after bypassing security
Police at Munich airport detained a passenger who left a terminal via an emergency exit instead of going through passport control, prompting a temporary partial shutdown of one of Germany's busiest airports Tuesday.
Up to 5,000 passengers were affected by the disruption as federal police searched for the unnamed passenger, Munich Airport spokesman Robert Wilhelm said.
Terminal 1 and parts of Terminal 2 were closed during the police operation. They were re-opened a few hours later.
Some 130 incoming and outgoing flights were canceled, German news agency dpa reported.
Affected passengers, who had already been through security checks for their departing flights, had to go through the process again, Wilhelm said.
Munich airport is one of Germany's busiest aviation hubs and the shutdown came during peak summer travel season.
Wilhelm said the passenger arrived on a flight from outside the European Union and was due to transfer at Munich airport. Before boarding the connecting flight the passenger had to go through security controls, but instead unlocked an emergency door and left through it despite setting off an alarm. It was not immediately clear from which country the person had arrived.
Last summer, some 330 flights were canceled in Munich when a woman entered a "clean area" of the airport without going through security checks, dpa reported.