SYRACUSE, N.Y. -- The Onondaga County Sheriff's Office is investigating after deputies discovered an assault rifle in a pile of trash on the city's West Side.

At about 7 p.m. Thursday evening deputies assigned to Operation IMPACT conducted a routine patrol on the West Side of the city of Syracuse. They found a large pile of trash and other debris near the backyard of an abandoned house on Putnam Street, the sheriff's office said.

In the middle of the pile of trash, under some roofing material, the deputies discovered an unloaded Smith and Wesson .22 caliber M&P 15-22 assault rifle.

The sheriff's office said the owner of the rifle still hasn't been found and that there was no one in the immediate area when the rifle was found.

Authorities are testing the rifle for ballistics and latent fingerprints.

Operation IMPACT is an initiative of the state Division of Criminal Justice Services that supports crime reduction initiatives in the 17 counties outside New York City that account for about 80 percent of the crime in upstate New York and Long Island.

The sheriff's office said it is continuing to investigate.