CHICAGO — The West Lawn community came together for a balloon release and prayer vigil in honor of a three-year-old boy shot and killed while riding inside a car with his mother Friday night.

Addressing gatherers Monday, the mother of Mateo Zastro says she will not rest until police capture her son’s killer.

Police said Mateo, 3, was sitting in the back seat of a car while his mother was driving on the 4400 block of West Marquette Road around 8:40 p.m. Friday, when someone inside a red sedan fired shots into the vehicle.

Mateo was shot in the head and transported to Advocate Christ Medical Center, where he was pronounced dead.

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Three other children were inside the vehicle but unharmed in the shooting.

An investigation is ongoing. Authorities are offering a $7,000 reward for information leading to an arrest.