Turlock Police say the suspect left a business located on South First Street when he opened fire at the victim and three other people.
The deputy suffered at least one gunshot wound and was transported to the hospital with critical injuries. He is expected to survive, police say.
Officials say the suspect fled the scene in a grey sedan or SUV. He is described as a Hispanic male, in his forties between 5'10" and 6'00" tall. He was wearing a blue polo shirt and blue jeans.
Anyone with information is asked to contact the Turlock Police Department at 209-668-5550.