EDS NOTE: GRAPHIC CONTENT - An injured man waits for help at the explosion scene that hit the seaport of Beirut, Lebanon, Tuesday, Aug. 4, 2020. Massive explosions rocked downtown Beirut on Tuesday, flattening much of the port, damaging buildings and blowing out windows and doors as a giant mushroom cloud rose above the capital. Witnesses saw many people injured by flying glass and debris. (AP Photo/Hussein Malla)

BEIRUT (AP) — A massive explosion rocked Beirut today, flattening much of the port, damaging buildings across the capital and sending a giant mushroom cloud into the sky. At least 50 people were killed and 2,700 injured, with bodies buried in the rubble, officials said.

Hours later, ambulances still carried away the wounded as army helicopters helped battle fires raging at the port.

The sudden devastation overwhelmed a country already struggling with both the coronavirus pandemic and an economic crisis: Beirut hospitals quickly filled beyond capacity, pleading for blood supplies and generators to keep their lights on.

The cause of the blast, which sparked fires, overturned cars and blew out windows and doors, was not immediately known.

Abbas Ibrahim, chief of Lebanese General Security, said it might have been caused by highly explosive material that was confiscated from a ship some time ago and stored at the port. Local television channel LBC said the material was sodium nitrate.

Witnesses reported seeing a strange orange-colored cloud over the site after the explosion. Orange clouds of toxic nitrogen dioxide gas often accompany an explosion involving nitrates.

An Israeli government official said Israel “had nothing to do” with the blast. He spoke on condition of anonymity because he was not authorized to discuss the matter with the media. Israeli officials usually do not comment on “foreign reports.”

The blast was stunning even for a city that has seen civil war, suicide bombings and bombardment by Israel. It could be heard and felt as far away as Cyprus, more than 200 kilometers (180 miles) across the Mediterranean.

“It was a real horror show. I haven’t seen anything like that since the days of the (civil) war,” said Marwan Ramadan, who was about 500 meters (yards) from the port and was knocked off his feet by the force of the explosion.

Health Minister Hassan Hamad said the preliminary toll was at least 50 dead and 2,700 wounded. Emergency teams streamed in from across Lebanon to help, and the injured had to be taken to hospitals outside the capital. Hamad added that hospitals were barely coping and offers of aid were pouring in from Arab states and friends of Lebanon.