BERLIN (AP) — German police advised travelers on Sunday not to use Hamburg airport due to a developing hostage situation.

The airport in the northern part of the city has been closed to passengers and flights canceled since Saturday night when an armed man broke through an airport gate with his vehicle and fired twice into the air with a weapon, according to German news agency dpa. Authorities also said the man’s wife had previously contacted them about a child abduction.

Police said that the 35-year-old man had his 4-year-old daughter inside the car whom he had reportedly taken by force from the mother in a possible custody battle.

A psychologist has been negotiating with the man for hours and there was no indication other people could be harmed since all passengers had evacuated the airport, police said.