Four armed men have entered an apartment in the western Belgian city of Ghent and taken a man hostage, media reports said, citing local police and the state prosecution service on Monday. Police have reportedly closed the surrounding area and urged people to remain indoors.

Authorities are reportedly unclear about the incident and the motive two hours after the armed men entered the building in the Dampoort district of the city. Filip Rasschaert, the head of Ghent Police, told De Standaard, a local news outlet, that a large-scale police operation is underway and that federal authorities were carrying out the operation in such a way as to account for the presence of a hostage inside the apartment, The Daily Mail reported.

"They have all they need to bring a successful end to a hostage-taking," Rasschaert reportedly said.

Federal police spokeswoman Annemie Serlippens said that initially the incident did not seem to be an act of terror, The Associated Press reported. 

"They're in the building but it's not clear what's going on inside," a police spokesman said about the Ghent incident, according to BBC.

"This isn't the same sort of incident as the events in Sydney," spokeswoman Serlippens said, according to BBC. An armed gunman is holding several people hostage at a cafe in Sydney's Martin Place, forcing a number of them to hold up a black Islamic flag.