Defense Secretary Mark Esper Wednesday contradicted President Trump's initial assessment that the massive explosion in the Lebanese capital of Beirut this week was an attack and likely caused by a bomb.

Asked about the tragedy at the Aspen Security Forum, Esper said he's still getting information but "most believe that it was an accident as reported and beyond that, I have nothing further to report on that. It’s obviously a tragedy."

TRUMP SAYS LEBANESE EXPLOSION WAS CAUSED BY 'A BOMB OF SOME KIND'

Trump talked of the explosion Tuesday from the White House and said U.S. military generals advised him it was an attack, likely caused by 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 Pentagon chief Wednesday made no mention of an attack or a bomb.

In this March 18, 2020, file photo, Defense Secretary Mark Esper speaks as President Donald Trump listens during a press briefing with the coronavirus task force, at the White House in Washington. (AP)

Esper said he spoke to Secretary of State Mike Pompeo and the U.S. stands ready to offer humanitarian assistance and medical aid to the people of Lebanon.

BEIRUT EXPLOSION LEAVES 300,000 HOMELESS, LEBANESE PORT OFFICIALS UNDER HOUSE ARREST

"We want to help," Esper said. "...We're positioning ourselves to provide them whatever assistance we can – humanitarian aid, medical supplies, you name it – to assist the people of Lebanon. It's the right thing to do. It's the humanitarian thing to do in the wake of this tragedy."

The massive explosion that tore through Beirut left some 300,000 people homeless, and Lebanese port officials have been placed on house arrest Wednesday amid an investigation into what caused the blast that so far has killed at least 135 people and injured thousands more.

Beirut’s Gov. Marwan Abboud said Wednesday that some 300,000 people might not be able to return to their homes for two to three months as the rescue crews continue to sift through collapsed buildings and rubble for survivors, UK’s The Telegraph reported.

International aid flights have begun to arrive as hospitals in the country already suffering from a severe economic crisis are overwhelmed with the wounded. One hospital damaged by the blast had to evacuate patients to a field for treatment. Abboud said he expects the death toll to continue to rise as hundreds of people have been reported missing.

BEIRUT EXPLOSION: RESCUE WORKERS FRANTICALLY SEARCH FOR SURVIVORS AS LEBANON CAPITAL CONFRONTS MASSIVE DEVASTATION

Lebanon’s President Michel Aoun vowed before a cabinet meeting on Wednesday that the investigation would be transparent and that those responsible will be punished.

“There are no words to describe the catastrophe that hit Beirut last night,” he said.

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Fox News’ Danielle Wallace, Lucas Tomlinson, Andrew O'Reilly and The Associated Press contributed to this report.