CHICAGO (CBS)– Three men are dead and at least 13 people were wounded in shootings in Chicago from Friday night through Sunday morning.

The first fatal shooting happened early Saturday at a Humboldt Park apartment where two brothers were playing video games.

Devon Greer, 21, and his brother were inside an apartment in the 3800 block of West Augusta Boulevard when someone fired shots from outside about 3:40 a.m., authorities said.

Greer, of south suburban Lansing, soon realized he was shot in the back, police said, adding that the brother was not injured. Paramedics took Greer to Mount Sinai Hospital, where he died at 5:22 a.m., according to the Cook County Medical Examiner’s office. An autopsy Sunday found that he died of a gunshot wound to the back.

The second fatal shooting occurred when a 22-year-old man was shot while standing in a parking lot early Sunday in the South Side Greater Grand Crossing neighborhood.

Shots rang out while the man was standing in a parking lot in the 7500 block of South Rhodes Avenue at 2:40 a.m., police News Affairs Officer Robert Perez said. He suffered multiple gunshot wounds to the chest and shoulder.

The 22-year-old man, Johnny White, of an unknown home address, was pronounced dead at 3:32 a.m. at Northwestern Memorial Hospital, according to the medical examiner’s office.

The most recent fatal shooting happened about 10:15 a.m. on Sunday.

Two young men, who are believed to be 17 and 21 years old, were shot at that location, according to Perez.

The 21-year-old was dead on the scene, according to police. A spokeswoman for the medical examiner’s office confirmed a fatality at that location, but could not provide any details on the victim, pending notification of next of kin.

The younger victim was taken to John H. Stroger Jr. Hospital of Cook County, where his condition was stable, according to police.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2012. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)