A hostage drama erupted in Sydney on Monday that mounted fears for an ISIS-linked attack in Australia. The dreaded terrorism incident occurred in a café during the city's morning rush hour. Based on several reports, five people have already escaped however, the exact number of hostages are still unknown.

The Sydney hostage crisis has already passed its 12^th hour Monday night and basic inquiries have remained unanswered. Yahoo! News reported a gunman held an unknown number of hostages at the Lindt Chocolat Café in downtown Sydney. According to the witnesses, two hostages were seen inside the café holding a flag with an Islamic declaration of faith, which has been often used by ISIS militants.

Though five people have been freed, the Sydney hostage standoff continues. As reported by The Washington Post, the all-day siege have taken employees and customers in captivity at a café in the city's main financial and shopping district.

At about 9:45 a.m. Sydney time, witnesses said they saw a man with a gun entered the Lindt Chocolat Café in Martin Place, a plaza in central Sydney, and locked the door. Hostages were then seen with their hands raised and two held a black flag with Arabic text. According to ABC, the Arabic sign means "There is no God but Allah" and "Mohammed is the Messenger of God."

The Australian authorities have declined to give further information about the Sydney hostage crisis. They refused to say how many hostages were inside the café, the motives of the gunmen, their demands and if the freed hostages were released or have escaped.

"I would like to give you as much as I can but right now that is as much as I can," New South Wales state police Commissioner Andrew Scipione said. "First and foremost, we have to make sure we do nothing that could in any way jeopardize those still in the building."

"Our only goal tonight and for as long as this takes is to get those people that are currently caught in that building out of there safely," he added.

The ongoing Sydney hostage crisis have sparked fears among Australians for a possible ISIS-linked blitzkrieg. Australia has pledged their support in the US-led coalition to destroy and pulverize the dreaded Islamic State extremists. However, The Daily Beast said it is currently unknown if Australia's involvement in the coalition against ISIS might have been a motivating factor in the incident.

Meanwhile, the flag used by the hostage-takers were believed to be connected with the ISIS. According to Bloomberg, former military intelligence officer Clive Williams said the flag appeared to be "Shahada," which is used by some Islamic State followers but he stressed that it wasn't the terrorists' official emblem.

Australian Prime Minister Tony Abbott also expressed his thoughts on the ongoing hostage crisis in Sydney. As per the BBC News, he said that it was deeply shocking that people were being held hostage by a gunman "claiming political motivation."

"Australia is a peaceful, open and generous society - nothing should ever change that and that's why I would urge all Australians today to go about their business as usual," Abbott said.

As the Sydney hostage crisis unfolded, CNN reported hundreds of police officers, some were armed with sniper rifles, have surrounded the area. While Australia's most populous city is currently on a lockdown.

Meanwhile, Lindt Chocolat Australia, the company that runs the café where the hostage taking took place, posted a message on its Facebook page saying that they are profoundly concerned over the incident.

Still in Australia, Muslim leaders have condemned the Sydney hostage crisis and they call it as "a criminal act."

"Such actions are denounced in part and in whole in Islam," the Grand Mufti of Australia and the Australian National Imams Council said via a Facebook statement.

The New South Wales Police has said that their approach to the ongoing Sydney hostage drama is to resolve it peacefully, though it might take some time, the department said it is their main priority.