Update at 1:33 a.m. ET
An undisclosed number of hostages are being held at a chocolate shop and cafe in Sydney, Australia. Reuters is reporting that police say they've made contact with the gunman and that TV footage showed three then two more people running from the scene. The number of hostages is said to be "not as high as 30," according to New South Wales Deputy Police Commissioner Catherine Burn.
As The Associated Press reported earlier in the day, TV footage had shown individuals holding their hands up against the window, as well as "what appeared to be a black flag with white Arabic writing on it."
"We don't yet know if this is politically motivated, although there are some indications that it might be," Australian Prime Minister Tony Abbott said of the situation, according to Reuters.
Nearby offices have been evacuated, and police have sealed off Martin Place, the central business district where the Lindt cafe is located.
The United States has evacuated its consulate in the city and issued a warning to Americans in Sydney, Reuters reports.
Events are still unfolding; we'll update this post as news comes in.