(CNN) -- A former Utah policeman is a suspect in at least three of Monday's four rush-hour shootings near Dallas, Texas, including one of two fatal attacks, police said Tuesday. 

CNN affiliate KSL in Salt Lake City, Utah, provided this file photo of the Dallas suspect, Brian Smith. 

The suspect, Brian Smith, tried to commit suicide after the Monday-evening shootings and was in a hospital in serious condition, Dallas police detective Lt. Craig Miller said. 

Police used ballistic tests to link Smith, a Utah state police officer for 12 years, to the shootings in which one driver was killed, one was injured by shattered glass and one escaped uninjured, Dallas police detective Lt. Craig Miller said. 

Miller said it is unclear if Smith was involved in the other fatal shooting, which was the first attack of the evening. 

Four motorists were attacked along a three-mile stretch near and on the LBJ Freeway, about 10 miles northeast of downtown Dallas, on Monday evening, police said. 

The first attack, which happened in Garland, Texas, about 5:41 p.m., killed Jorge Lopez. Garland police said Lopez, 20, was sitting in his Nissan at a traffic light when a man in a pickup pulled alongside him and fired shots into his car, killing him. A few minutes after the Garland shooting and two miles away on LBJ Freeway, a gunman fired at two tractor-trailers. 

While one driver escaped injuries, William Scott Miller, 42, of Frankfort, Kentucky, was shot to death behind the wheel of a United Van Lines truck, police said. 
Who was the suspect?
Dallas suspect, Brian Smith