At least 100 dead, more than 4,000 injured in Beirut explosion: Lebanese Red Cross

The cause of the blast is unknown

In a short televised speech Wednesday morning, Lebanese Prime Minister Hassan Diab appealed to the world for help, one day after a devastating explosion at Beirut’s port killed at least 100 people and injured more than 4,000 -- with both numbers expected to rise.

"We are witnessing a real catastrophe," Diab said, reiterating his pledge that those responsible will be punished -- although the cause remained unclear, according to the Associated Press.

Smoke was still rising from the port Wednesday, where towering grain silos had been shattered and many buildings damaged.

George Kettaneh, secretary-general of the Lebanese Red Cross, said the numbers may rise. Officials have said the city’s hospitals are overflowing with patients.

The explosion sent a huge mushroom cloud into the sky and flattened much of the port. Beirut newspaper al-Akhbar dubbed the explosion “The Great Collapse," and it was believed to be the largest blast the Middle Eastern capital has ever endured.

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President Trump said U.S. military generals told him it was likely a bomb.

"I've met with some of our great generals and they just seem to feel that this was not some kind of manufacturing explosion type of an event," Trump said. "They seem to think it was an attack. It was a bomb of some kind."

The explosion could have also been caused by highly explosive material that may have been confiscated from a ship and stored at the port, according to the chief of Lebanese General Security.

The fire was likely ignited by fireworks and ammonium nitrate, experts have suggested, according to the AP.

Local television channel LBC said the material was sodium nitrate.

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Earlier, the health minister reported at least 70 killed and more than 3,000 injured.

Fox News' Bradford Betz, Danielle Wallace and Dom Calicchio and the Associated Press contributed to this report.