The Illinois city banned assault weapons nearly a decade ago, a move that was challenged and ultimately upheld by the Supreme Court.

The July Fourth parade attack suspect legally purchased multiple weapons prior to the shooting in Highland Park, Illinois, that killed six people, a senior law enforcement official told NBC News.

The official did not specify what weapons were purchased. Officials have said the weapon used in the massacre, which also injured more than two dozen people, was a high-powered rifle.

Authorities said the weapon was left behind at the scene, enabling them to trace it and identify a suspect. ...