A gunman has taken an unknown number of hostages in a café in central Sydney, Australia, but after 10 hours, the gunman's motivation is still unclear, according to USA Today.

Earlier, five hostages were able to escape Lindt Chocolat Cafe in Sydney's financial and shopping district.

"We have not yet confirmed it is a terrorism-related event," New South Wales state police Commissioner Andrew Scipione said, according to USA Today. "We're dealing with a hostage situation with an armed offender."

Hostages held up the black flag of Islamic State in the café window, an act that is believed to have been at the behest of the gunman.

Australian Prime Minister Tony Abbott told Australians to conduct their day as they would normally, but New South Wales Premier Mike Baird said there will be an "exclusion zone" surrounding Martin Place, the location of the hostage situation. People who work in that area must work from home, USA Today reported.

Abbott said the situation might be "politically motivated," and police have requested that the media not publish the gunman's demands.