BERLIN (AP) — Six climate activists broke through a security fence at Munich airport on Saturday and glued themselves to access routes leading to runways, temporarily shutting down flights.

The activists from the group Last Generation were protesting flying as the most polluting form of transportation, said the German news agency dpa. Police detained the six.

Some 60 flights were canceled during the disruption that lasted a couple of hours and passengers were rebooked on alternative flights, airport spokesperson Robert Wilhelm told dpa. Fourteen flights that were due to land in Munich were diverted to other airports, according to police.

Last Generation accused the German government of “downplaying” the negative effects of flying on the environment instead of “finally acting sincerely,” in a post on the social media platform X.

German Interior Minister Nancy Faeser called for an end to such protests. “Such criminal actions threaten air traffic and harm climate protection because they only cause lack of understanding and anger,” she wrote on X.

Fraser also applauded police efforts to bring order back to the airport and called for airport safety measures to be checked.

Minister for Transport Volker Wissing said that his ministry was already working on further tightening existing laws.

The general manager of the German Airports Association, Ralph Beisel, also criticized the activists’ actions. “Trespassing the aviation security area is no trivial offense. Over hundreds of thousands of passengers were prevented from a relaxed and punctual start to their Pentecost holiday,” he told dpa.

Beisel also called for harsher penalties for activists who break into airports.

Climate activities blocked flights at Hamburg and Duesseldorf airports for several hours in July.

In January, Last Generation — known for gluing themselves to streets to block traffic which has infuriated many Germans — said it would abandon the tactic and move on to holding what it calls “disobedient assemblies.” Their actions have been widely criticized, and Chancellor Olaf Scholz described them as “completely nutty.”