St. Louis County police say a man who was trying to rob three contractors working on a water-line project was killed after one of the workers shot him in the chest.

The St. Louis Post-Dispatch reports the shooting happened about 9 a.m. Monday in an unincorporated area of St. Louis County between Ferguson and Bellefontaine Neighbors.

Police say two workers for ADB Utility Co. were standing near a company truck when an armed man approached them and took their wallets by gunpoint before turning to a third man nearby. That's when police say the suspect was shot in the chest. He died at the scene.