The airport in Frankfurt, Germany, was shut down for nearly two hours Monday after a drone was spotted over its southern part, police said.

The airport was shut and the authorities searched the area with the support of a helicopter, after a pilot reported the drone around 11:15 a.m.

The police added that at 1 p.m. the airport was reopened but the investigation continued.

Several flights were canceled or rerouted, including the plane with the governor of the western German state of North...