CHICAGO — NBA star Dwyane Wade's cousin was an innocent bystander, police said, pushing her baby in a stroller near a Chicago school where she intended to register her children when she was fatally shot Friday.

Nykea Aldridge's famous relative, who grew up in Chicago's south suburbs, tweeted to his nearly 6 million followers about her death, saying Friday it was an "act of senseless gun violence" and posting Saturday morning that Chicago needs "more help& more hands on deck." Wade ended both days of tweets with the hashtag "EnoughIsEnough."

The 32-year-old mother of four recently relocated to an area on the city's South Side, her family said. She was near the school, which is about a mile and a half southwest of the University of Chicago, when two males walked up and fired shots at a third man but hit Aldridge in the head and arm. She wasn't the intended target, police said.

Police are questioning witnesses in the shooting but had no suspects in custody.

Chicago has been plagued by gun violence for years, especially in a few South and West Side neighbourhoods. This July alone, there were 65 homicides — the most that month since 2006.

Wade, whose charitable organization, Wade's World Foundation, does community outreach in the Chicago area, signed with the Chicago Bulls in July after 13 years with the Miami Heat. He and his mother, pastor Jolinda Wade, participated Thursday via satellite in a town hall meeting in Chicago on gun violence hosted by ESPN.

"My cousin was killed today in Chicago. Another act of senseless gun violence. 4 kids lost their mom for NO REASON. Unreal. #EnoughIsEnough," he tweeted Friday.

Wade also tweeted Saturday morning: "The city of Chicago is hurting. We need more help& more hands on deck. Not for me and my family but for the future of our world. The YOUTH!" adding in a following tweet, "These young kids are screaming for help!!! #EnoughIsEnough."

Outside the emergency room where Aldridge was pronounced dead, Jolinda Wade clutched her sister and spoke for the family as mourners stood in a circle holding hands and praying. She said she'd participated in the town hall meeting "never knowing that the next day we would be the ones that would actually be living and experiencing it."

"We're still going to try to help and empower people like the one who senselessly shot my niece in the head," Jolinda Wade said. "We're going to try to help these people to transform their minds and give them a different direction."

It is not the first time Dwyane Wade's family in Chicago has been affected by gun violence. His nephew, Darin Johnson, was shot twice in the leg in 2012 but recovered.

Chicago had recorded 381 homicides by the end of July, up 30 per cent from the same period of 2015. Its murder rate is higher than the more populous cities of New York and Los Angeles.

Republican presidential candidate Donald Trump has spoken about the city's violence, and tweeted about Aldridge's death Saturday morning. He first posted, "Dwyane Wade's cousin was just shot and killed walking her baby in Chicago. Just what I have been saying. African-Americans will VOTE TRUMP!," and then tweeted, "My condolences to Dwyane Wade and his family, on the loss of Nykea Aldridge. They are in my thoughts and prayers."

Family members are caring for Aldridge's baby, who wasn't hurt.