(CNN) A teenager dedicated to fighting Chicago's gun violence was shot and killed outside his brother's basketball practice, police and his family said.

Delmonte Johnson, 19, was on the sidewalk of a South Side street on Wednesday when someone shot him multiple times from a tan-colored car, police said.

"He laid there with his brother on the ground as he bled out from gunshot wounds... it's sad," his mother, Onique Walker, told CNN affiliate WLS

Johnson was shot in the chest and stomach. He was taken to a hospital, where he later died, WLS reported.

Police are searching for a suspect and are offering a $1,000 for information that leads to an arrest.

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