Major police operation unfolding at Sydney; people inside shop seen with arms in the air

This image taken from video shows people holding up hands inside a cafe in Sydney, Australia Monday, Dec. 15, 2014. A gunman took an unknown number of people hostage inside the downtown Sydney chocolate shop and cafe at the height of Monday morning rush hour, with two people inside the cafe seen holding up a flag believed to contain an Islamic declaration of faith. (AP Photo/Channel 7 via AP Video) AUSTRALIA OUT (The Associated Press)

Police stand at the ready close to a cafe under siege in Martin Place in the central business district of Sydney, Australia, Monday, Dec. 15, 2014. New South Wales state police would not say what was happening inside the cafe or whether hostages were being held. But television footage shot through the cafe's windows showed several people with their arms in the air. (AP Photo/Rob Griffith) (The Associated Press)

This image taken from video shows a man believed to be a gunman inside a cafe in Sydney, Australia Monday, Dec. 15, 2014. An apparent hostage situation was unfolding inside the chocolate shop and cafe in Australia's largest city on Monday, where several people could be seen through a window with their hands held in the air. (AP Photo/Channel 7 via AP Video) AUSTRALIA OUT (The Associated Press)

A major police operation is underway in downtown Sydney, where several people inside a shop could be seen holding their hands held in the air.

New South Wales state police would not say Monday what was happening inside the shop or whether hostages were being held. But television footage shot through the windows of the shop showed several people with their arms in the air and hands pressed against the glass.

Police officers were lined up outside the shop.