CHICAGO (CBS) — Three men were killed and at least 21 other people have been wounded in shootings across Chicago since Friday afternoon, marking a violent Christmas holiday weekend.

The most recent fatal shooting happened shortly at 12:14 a.m. Christmas Day in the Chatham neighborhood on the South Side. Albert Abu, 57, was standing on the sidewalk in the 8100 block of South Wabash when two males walked up and opened fire, according to Chicago Police and the Cook County medical examiner’s office. Abu, who lived on the same block, suffered gunshot wounds to the head and chest and was taken to St. Bernard Hospital, where he was pronounced dead at 12:28 a.m.

A 19-year-old man was gunned down at 5:31 p.m. Saturday in the Roseland neighborhood on the Far South Side. A witness said 19-year-old Janaria T. Moore was standing in the 11200 block of South Michigan when someone got out of a dark-colored SUV and fired shots before taking off in an unknown direction, police and the medical examiner’s office said. Moore suffered a gunshot wound to his back and was pronounced dead at the scene at 5:42 p.m., police and the medical examiner’s office said.

About three hours earlier, a 21-year-old man was killed and a 25-year-old man was wounded in an Austin neighborhood shooting on the West Side. The men were sitting on a back porch at 2:34 p.m. in the 5200 block of West Ferdinand when another male walked up, fired shots and ran off in an unknown direction, authorities said. The younger man suffered multiple gunshot wounds to the head and body and was pronounced dead at the scene at 3:12 p.m. His identity has not been released. The older man was shot in the ankle and taken in good condition to Stroger Hospital.

The most recent nonfatal shooting happened about 6:15 p.m. Sunday in the South Loop. A 31-year-old man was walking out of a store in the 1200 block of South Jefferson when a 34-year-old man pulled out a gun and demanded money, police said. After the robber stole his property, the 31-year-old man shot him in the chest. The suspect was arrested and taken in critical condition to Stroger Hospital.

At least 19 other people have been wounded in shootings across Chicago since the start of Christmas weekend Friday afternoon.

Last year, 59 people were shot in Chicago over the holiday weekend, leaving 11 dead.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2016. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)