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PHILADELPHIA (CBS) — Three men are dead after a car explosion in Allentown on Saturday evening.

Officials believe the explosion was an isolated incident and say there is no threat to public safety.

“We have a high degree of confidence the perpetrator was probably killed in the incident,” said Lehigh County District Attorney Jim Martin in a news conference Sunday morning.

Lehigh County Coroner Scott Grim says authorities are working to identify the victims and autopsies will be performed Monday.

Allentown police received multiple calls around 9 p.m. about hearing and feeling a possible explosion.

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When fire crews arrived at the intersection of North Hall and West Turner Streets, they found the car fully engulfed in flames.

The ATF is leading the investigation with the help of the Allentown Police Department, Pennsylvania State Police and the FBI.

A witness shared footage of the explosion on social media, which shows the aftermath of the explosion.

“We are working with our law enforcement partners to assess the situation & determine the cause, with public safety the Bureau’s highest priority,” the FBI tweeted early Sunday.

“I heard a big explosion, I ran to the window to see what it was, I didn’t see anything. But after that, I seen the fire,” recalls eyewitness Antonia Santiago. “People couldn’t even get their cars out. It’s crazy. It’s got me nervous.”

Officials say the investigation expands from Sixth and Ninth Streets and Linden and Chew Streets.

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The Red Cross has set up a shelter for displaced residents at Cleveland Elementary School on North 9th Street.

Investigators are asking anyone who may have seen or heard something suspicious around the time of that explosion to please give them a call as soon as possible at 888-ATF-BOMB or .