At least six people have been killed and 53 wounded when an explosion rocked a busy pedestrian street in central Istanbul.

Ambulances rushed to the scene on packed Istiklal Avenue, which police quickly cordoned off. The area in the city’s Beyoglu district had been crowded with shoppers, tourists and families.

President Recep Tayyip Erdogan said that initial signs pointed to a “terror” attack.

“It might be wrong if we say for sure that this is terror, but according to first signs, … there is a smell of terror there,” Erdogan said at a televised news conference.