A massive fire erupted at a crude oil refinery in Philadelphia on Friday morning, June 21, triggering several explosions and sending flames high into the sky.

Authorities said the fire broke out about 4 a.m. in a butane vat at Philadelphia Energy Solutions Refining Complex, which claims to be the largest oil refining complex on the East Coast. Nearby residents said the eruption was so fierce it shook picture frames from the walls and could be felt miles away in South Jersey, according to local reports.

It was not immediately clear how the fire started, but authorities said there were no immediate reports of injuries.

Philadelphia Deputy Fire Commissioner Craig Murphy said during a morning news conference that the fire is currently contained inside the vat and the Philadelphia Fire Department is supporting the Philadelphia Energy Solutions fire brigade to ensure that the blaze does not spread.

"This is going to be a long operation," he said. "It's confined, and it's being addressed, but it is not under control."

The fire commissioner said an initial shelter-in-place request has been lifted after Philadelphia Energy Solutions sent an industrial hygienist to test the air and it was "clear." Philadelphia Energy Solutions will continue to monitor the air in the area, he said.

The Associated Press reported that this is the second fire at the refinery in the past month.

Philadelphia Energy Solutions could not immediately be reached for comment on the fire.

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This article was written by Lindsey Bever, a reporter for The Washington Post.