A 3-year-old boy being taken on a shopping trip by his grandmother was killed in a road rage shooting when a driver opened fire on the grandmother's car because he thought she "wasn't moving fast enough at a stop sign," police said.

The boy and his grandmother were at the stop sign in southwest Little Rock on Saturday evening when a driver, apparently angry about the delay, stepped out of his car and opened fire, police said. The boy was struck by gunfire at least once, they said.

The grandmother, who wasn't struck, drove away and called police from a shopping center.