Authorities sealed off surrounding streets, evacuated people from buildings, and suspended rail services following the incident at the Lindt Chocolate Cafe in Martin Place, in the heart of the city’s business district.
Martin Place is a public pedestrian thoroughfare through the heart of Sydney, joining its parliamentary, legal and retail districts.
Television footage showed people inside the cafe with their hands pressed against the window holding the black flag known as Shahadah, a prayer spoken in mosques daily, and not a flag specific to the Islamic State.
Lindt Australia executive says there are about 10 staff and up to 30 customers trapped in the cafe. Police declined to comment on the number of hostages involved.