ALLENTOWN, Pa. >> A car exploded on a downtown street in what authorities called a “criminal incident,” leaving three people dead and leading to a shelter-in-place order for nearby residents and an investigation by federal, state and local authorities.

The blast in Allentown that occurred at about 9:30 p.m. Saturday left three males dead, Lehigh County Coroner Scott Grim said Sunday afternoon. Autopsies were planned Monday, and Grim said the names of the males would be released once their identities are confirmed and their families are notified.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives is leading the investigation along with the FBI, state police, and city and county authorities. Officials said the blast was believed to have been an isolated incident with no ongoing threat to the public.

“We know there’s been a criminal incident,” District Attorney James Martin told reporters at a news conference today. “We have a high degree of confidence that the perpetrator was probably killed in the incident.”

Authorities released no information about the possible cause of the blast, but Martin said “loads of us in law enforcement” are confident “this was A. an isolated incident and B. there’s no continuing threat.”

Resident Carlos Perodin told the Morning Call of Allentown that he was watching a movie with his wife when he heard a thunderous explosion and went to the scene.

“The fire was crazy,” he said. “The car was pretty much split in half.”

Another witness to the aftermath of the explosion, Stephanie Connelly, told the Morning Call that she saw body parts strewn across the street.

“This is real life and I’m shaking and freaking out while I’m running,” she said.

A bus station was turned into a makeshift command center with armored vehicles, dozens of police cruisers, mobile command units and even portable bathrooms, the paper reported. Several portable tents were also erected for evidence processing.

Residents were asked to avoid the area, and people who live nearby were asked to shelter in place. A shelter was set up at an elementary school.

The FBI had earlier said it was working with other agencies and “to assess the situation and determine the cause, with public safety the bureau’s highest priority.” Officials asked anyone who witnessed the blast or had information about it to contact investigators.