PHILADELPHIA (CBS) — Federal and local authorities are investigating after an explosion injured a man in a Rittenhouse Square apartment early Tuesday morning.

Police rushed to the 1800 block of Pine Street when a suspicious package exploded inside a man’s apartment around 4 a.m.

A high-ranking official within the Philly Police Department tells CBS News that the suspicious package was in fact a device, that it was victim-activated and came in a manila envelope.

Investigators are trying to determine if the package was hand-delivered or mailed to the victim.

CBS 3 has identified the victim has 60-year-old Jim Alden. Sources say Alden works for Brulee Catering.

“We are very saddened to learn that one of our hourly employees has been injured. During this time we have been cooperating with the investigation of this morning’s incidents. We wish him a speedy recovery,” the company said in a statement, adding that they are “cooperating with the investigation.

Chief Inspector Scott Small says the explosion occurred inside the kitchen where the man lives.

“There’s some broken glass, there’s some damage to the range where you would cook, there’s some blood, but there’s not a lot of structural damage at all inside the property,” Small said.

According to CBS 3, a box with a bar code was placed on the steps in front of the building. When the victim decided to open the package this morning it exploded.

Authorities say the package had a power source and loop switch. When it detonated there was a smell of Sulfur in the apartment.

Sam Rabadi, special agent in charge of the ATF, says investigators have not determined why Alden was targeted.

“It was a padded envelope and upon it being opened by the victim. It detonated. It exploded,” Rabadi said.

What remained of the bomb was sent to ATF labs in Virginia to be quickly processed.

“It’s not something we’ve typically seen out there,” Rabadi said. “It’s a little different. “

Alden was transported to Jefferson Hospital after suffering injuries to both hands, face and upper body. Authorities say the victim had to undergo surgery for his injuries.

He’s listed in stable condition.

The Philadelphia Police, Bomb Squad, the ATF and other agencies continue to investigate this incident, but say there’s no threat to the surrounding area.

“All of the other mailed packages that we initially thought were suspicious have been cleared,” Small said.

Police are talking to the victim and his partner and looking at everything, including the possibility of this being a hate crime.

This incident is not believed to be terrorism, authorities say.