A drug deal went bad in Santa Rosa Tuesday when it turned into an armed robbery and led to a police pursuit.

The armed robbery was reported at 3:05 p.m. at a Versailles Street home on the west end of town, Santa Rosa Police Sgt. Tommy Isachsen said.

Responding officers spotted a car matching the description given by the victim and began pursuit. During the chase, police said, a passenger tossed a backpack out of the car.

The car was stopped shortly after, and officers detained four suspects.

Upon recovering the backpack, they found several hundred dollars in cash, a loaded pistol and a small bag with a white substance, which police said appeared to be cocaine.

Roberto Laron Alvarez, 24, of Santa Rosa, was arrested on suspicion of robbery and assault with a deadly weapon, as well as other charges. Alvarez, a passenger in the car, already was wanted on a warrant for possession of a controlled substance, police said.

The other three people detained at the scene were released. “At this time we don’t believe they were all acting in concert,” Isachsen said.

Police are not releasing their names or the name of the victim at this time, as the investigation is ongoing.