A package exploded in a downtown Philadelphia apartment early Tuesday after a man opened the manila envelope believing it contained an inhaler, police said.

According to Philadelphia Police Commissioner Richard Ross, the man received the package Monday evening and opened it early Tuesday, apparently believing it contained an inhaler or other type of medicine.

The package, he said, was “target specific,” and that it included an “actual device” that was meant to injure.

Other details about the device were not immediately available. It wasn’t clear if police know or suspect who sent the package.

The 62-year-old man, whose name has not been released, was hospitalized with hand and chest injuries.

Agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives worked to determine the cause of the blast that injured the man around 4:30 a.m.

"As far as I know, there were no threats prior to this and no threats since," Police Chief Inspector Scott Small said.

Police said the victim opened the package near the stove in the kitchen of the apartment he shares with a roommate, leading police to initially believe the blast may have been an accidental explosion caused by an inhaler getting too close to heat.

Fox 29 News reported that inhalers delivered in the mail had been known to explode in the past.

The damage from the blast was confined to the kitchen and included broken glass, Small said.

The victim was taken to Thomas Jefferson University Hospital and was in stable condition.

U.S. Postal Inspectors and the city bomb squad are also working together to determine the cause of the blast.

Ten residents were evacuated from nearby apartments, but were allowed to return after the bomb squad cleared other packages.

The victim's roommate reportedly told police that the man often receives medical inhalers in the mail.

FOX 29 News reported authorities do not believe the package was delivered by the U.S. Postal Service and that it had a very old barcode on it.