A suspected robber was hospitalized Wednesday evening with a gunshot wound suffered during the holdup of a man in Collier, Allegheny County Police said.

Three people, including the robbery victim, have been arrested, and a fourth arrest was pending yesterday, police said.

The victim, Joshua Oravetz, 21, of Scott, called 911 at 8:04 p.m. to report the robbery on Boyds Run Road in Collier.

The suspected robbers had fled by the time police arrived. One of them, Dupree Patterson, 31, of McKeesport, had been shot in the forearm and thigh. His companions drove him to St. Clair Hospital for treatment.

County police Lt. William Palmer said Mr. Patterson and two others, Crystal Carson, 19, of Bridgeville, and Michael Harshey, 21, of the North Side, tried to rob Mr. Oravetz at gunpoint. Mr. Oravetz pulled a pistol of his own and began firing, causing his attackers to flee, Lt. Palmer said.

Police suspect Mr. Oravetz had been selling marijuana and that the other three tried to rob him of his money and drugs.

Mr. Oravetz was arrested on charges of aggravated assault and illegal possession of a firearm. Ms. Carson and Mr. Harshey were arrested on robbery charges. All three were arraigned yesterday.

Mr. Patterson was to be charged upon his release from the hospital, Lt. Palmer said.