By Greg Argos, Kristen Johanson

PHILADELPHIA (CBS) – The Philadelphia Police Department along with the FBI are looking into a possible new threat related to the ambush shooting of officer Jesse Hartnett.

READ MORE: Man Charged After Juvenile Shot In Alleged Road Rage Incident In Lehigh County, Police Say

City and federal law enforcement officials are investigating a citizen tip warning of possible additional attacks on Philadelphia police.

Investigators say someone approached a Philadelphia Police officer over the weekend, and claimed the man who shot Officer Hartnett —  30-year-old Edward Archer — is part of a larger, radical group — and that a threat may still exist.

The tip said Archer is “part of a group that consists of three others.” She went on to say that archer “is not the most radical of the four” and that “the threat to police is not over.”

Police and the FBI are trying to determine whether or not the information is credible. For now, the department says all officers must work with a partner.

READ MORE: Flyers Ripped By Hurricanes For 5th Straight Loss

In a statement, Police Lt John Stanford says they take this kind of information very seriously, particularly after the attack on Hartnett (see full statement below).

Archer claimed to have shot Officer Hartnett for religious and political reasons. The officer is still recovering from three bullet wounds to his arm.

RELATED: Photo Gallery: Officer Hartnett Recovering After Shooting In West Philly

Here is the full statement released by Philadelphia Police.

Last night a Philadelphia Police Officer was stopped by a citizen on the street who proceeded to make statements regarding the defendant involved in the shooting ambush on Officer Hartnett, which occurred on January 7, 2016. The citizen alleged the defendant had an affiliation to a group with radical beliefs.

The Philadelphia Police Department and Federal Partners take this type of information very seriously, particularly after the recent attack on Officer Hartnett. Therefore, the department along with the Federal Bureau of Investigation is actively investigating these allegations in an effort to verify the credibility of the information given.

The Philadelphia Police Department has alerted all department personnel of this matter and will continue to have officers work with a partner until further notice.
As always, we encourage any information or tips from members of the community regarding this matter.

MORE NEWS: Stray Bullet Kills Man Eating Thanksgiving Dinner Inside Norristown Home, Police Say