Police were investigating a spate of violence in which six people were wounded in three incidents within about three hours Thursday night and yesterday morning.

In the first incident, three unidentified men approached two men on Olive Street near 49th in West Philadelphia shortly after 11 p.m. Thursday and asked if they had marijuana, according to Officer Christine O'Brien, a police spokeswoman.

Both men said no, and one of the suspects started firing, police said. One man, 24, was shot several times in the chest and taken to the Hospital of the University of Pennsylvania, where he was listed in guarded condition.

The other man, 45, tried to run but was shot in the back, police said. He also was listed in guarded condition at HUP.

About 25 minutes later, investigators responded to a shooting on 52nd Street near Springfield Avenue in Kingsessing, where a 16-year-old boy told police that he had been sitting in his house talking on the phone when he heard a knock on the door.

When he opened it he was shot once in the left side of the neck, police said.

He was taken to HUP, where he was listed in stable condition.

About two hours later, police were called to a triple shooting on Baltimore Avenue near Allison Street in West Philadelphia.

"Officers were in the area and heard multiple gunshots," O'Brien said.

They found two men, ages 48 and 33, on the street with multiple gunshot wounds, and another man, 29, who ran inside the Commodore Bar with a leg wound, O'Brien said.

The 48-year-old and 33-year-old were taken to HUP, where they were listed in critical condition, police said.

The 29-year-old was treated at Hahnemann University Hospital and released.

Police were still trying yesterday to determine motives and develop information on suspects.

Tipsters can contact Southwest Detectives at 215-686-3183 or the citywide tipline at 215-686-TIPS.