UPDATED 07/19/11 6:07 a.m.

CHICAGO (CBS) — Police shot and killed a suspect early Tuesday in the South Side’s Washington Heights neighborhood, after he pointed a gun at officers who had earlier witnessed another shooting involving the suspect.

Around 12:55 a.m., Morgan Park District police officers were patrolling around 91st Street and Ashland Avenue when they saw a man fire a gun and shoot two other men.

They chased the gunman to an alley behind the 9200 block of South Justine Street, police said. While the fleeing gunman was attempting to climb over a fence, he pointed his weapon at the officer chasing him on foot, Chicago Fraternal Order of Police spokesman Pat Camden said.

Officers returned fire and shot the victim, who was later pronounced dead at Advocate Christ Medical Center in Oak Lawn.

The man shot dead by officers is now identified as Parise R. Mercer, Jr., 18, of the 9000 block of South Marshfield Avenue, according to the Cook County Medical Examiner’s office.

The two men earlier shot by the suspect were taken to Little Company of Mary Hospital and Health Care Center in Evergreen Park with non-life-threatening injuries, he said.

This is the sixth police-involved shooting within the last 72 hours, Camden said.

“It looks like police are under siege,” Camden said. “If offenders are shooting at police, what are they doing to the average citizen?”

This was also the second police-involved shooting in about two hours. Around 10:45 p.m. Monday, two officers were shot and wounded as they tried to confront a suspect in a drug deal near Karlov and Gladys avenues on the city’s West Side.

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