German police advised travellers 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 cancelled 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.

“We must currently assume that he is in possession of a live firearm and possibly also explosive devices of an unknown type,” police wrote on X, formerly known as Twitter.

“Our top priority is to protect the child. According to our current knowledge, the child is physically well,” they added.

The mother of the abducted girl also arrived at the airport and was getting psychological support, German news agency dpa reported.

“The mother naturally wants to get to her child as quickly as possible,” Malte Stueben, the head of the German Red Cross crisis intervention team in Hamburg, told dpa.

A pediatrician also arrived at the airport to look after the girl once the hostage-taking is over, dpa reported.

On Sunday morning, 126 flights were cancelled and five planes were rerouted. Thousands of travellers have been affected by the standoff and hundreds were put up at hotels close by.