FRANKFURT (Reuters) - Flights to and from Frankfurt airport, Germany’s largest, had to be suspended twice on Monday after drone sightings.

A spokesman for the operator Fraport said 72 flights had been canceled and 57 redirected during the two stoppages, which together lasted almost three hours.

Police said they were still looking for the perpetrators and their drones, and criminal proceedings were launched for dangerous interference in air traffic.

“In addition, the perpetrators must expect considerable claims for damages under civil law,” the police added.

In one of the worst air traffic disruptions from drones, reported sightings near London’s Gatwick airport caused chaos for hundreds of thousands of Christmas travelers in December 2018.