A huge explosion occurred in the Lebanese capital Beirut on Tuesday, wounding hundreds of people and blowing out windows across the city.

According to the state-run National News Agency, the explosion was initially believed to be caused by a fire at a firecracker warehouse located near the port in Beirut but the cause is not yet confirmed. Buildings that have been damaged from the blast include the headquarters of former Prime Minister Saad Hariri and CNN’s bureau in the city. Witnesses have said that homes located over five miles away from the site of the blast have been damaged.

Lebanon’s health minister has ordered all hospitals to prepare for casualties.