Four pedestrians were killed and at least 20 others injured Friday after a man deliberately drove his vehicle down a crowded sidewalk in Melbourne, Australia. A 10-year-old child is among the dead. Victoria Police say they have arrested the driver, though his identity has not yet been released. The incident is thought to have been prompted by a stabbing that took place earlier in the day, and police say they do not believe the attack is terrorism-related. The incident occurred in the Bourke Street shopping mall area around midday, authorities said. Witnesses interviewed by Sky News described a scene of chaos, saying several gunshots rang out before police took the suspect away. “There was just all this noise and mayhem and then all of a sudden police flying everywhere and just bodies lying all over the ground,” one unnamed witness was cited as saying. Another witness said the car appeared to have been traveling at more than 40 miles an hour, and the driver’s car had a wrecked child’s stroller on top of it.