A knifeman barricaded himself in a room with a pregnant woman at a refugee centre in Hamburg before being dramatically arrested, it has emerged.

Armed police were called amid reports a man with a weapon had stormed into the facility in Hammerbrook area of the German city this morning.

He is understood to have been holding a pregnant woman - believed to be his partner - hostage at the centre and was holed-up in a room.

A gunman has barricaded himself in refugee centre in the German city of Hamburg, it has been reported (file picture)

Footage online shows elite German officers with assault rifles storming into the building this morning at about 10.30am local time.

A pregnant woman in a yellow top was seen being led away from the building a short time later.

According to Bild, the man was overpowered by police and was seen on a stretcher being taken to an ambulance.

Hamburg police said the man had wounded himself during the operation, but the nature of his injuries is not yet known.

The police force had earlier taken to Twitter to say a major police operation was underway in the Hammerbook area.

Local media reported that the man was a refugee who had been living in another state within Germany.

It is not yet known why he barricaded himself in the building.