An armed militant reportedly took at least a dozen people hostage at a Lindt chocolate café in Sydney on Sunday. Police say the situation is ongoing.

The chocolate shop is located across the street from Sydney's Channel 7 news, which broke the story. Armored police vehicles are reportedly on the scene.

Hostages were required to hang a large black Islamic flag in the window, prompting some media outlets to report that ISIS is involved. However, the flag, which appears to be the Shahada, is widely used outside of ISIS and other terrorist organizations as a "general expression of faith" in Islam.

Update 7:20 p.m.

Despite reports that the airspace over Sydney was been closed, the Deputy Prime Minister's office told the Guardian that traffic was merely being rerouted due to police helicopters circling over the café.

And, also via the Guardian, AAP video of the scene nearby.

Update 7:30 p.m.

The Sydney Opera House, located about a half-mile from the café, was reportedly evacuated after a suspicious package was found. It's not clear if the package was connected to the café hostage situation.

Update 8:10 p.m.

The Shahada, pictured on the black flag, is an Arabic creed that is essential to Islamic culture, but often associated with various terrorist organizations, including ISIS, that have co-opted it.

The Arabic translates to: "There is no god but Allah, and Muhammad is his messenger."

Via the Georgetown University Berkley Center:

Muslims consider reciting the Shahada to be the first and most important of the Five Pillars of Islam, since understanding and accepting it means that one understands and accepts the essence of the entire faith. In fact, Muslims hold that belief in the content of the Shahada is the foremost distinguishing characteristic that defines a Muslim as a Muslim. A single earnest public recitation of the Shahada in its original Arabic is all that is required to convert to Islam.

Update 9:30 p.m.

Uber is price surging in Sydney now, charging customers a $100 minimum.

Update 11:15 p.m.

Earlier this evening, New South Wales state Police Commissioner Andrew Scipione told reporters police still hadn't made contact with the gunman and his motivation is still unknown.

''We have not yet confirmed it is a terrorism-related event,'' Scipione said. ''We're dealing with a hostage situation with an armed offender and we are dealing with it accordingly.''

Update 11:42 p.m.

7 News Sydney reports hostages have been spotted running out of the cafe.

Update 7:39 a.m.

Multiple outlets are reporting that at least five hostages—including two cafe employees—have fled the coffee shop, but as the New York Times notes, "it was not clear whether the assailant had allowed them to leave or they had escaped." It remains unclear how many hostages remain inside.

Update 10:47 a.m. The siege is now over.