A former US Navy SEAL sniper credited with killing more than 150 insurgents in Iraq has been shot to death at a firing range in Texas.

The death of Chris Kyle (38) was confirmed by FITCO Cares, a foundation he helped start that worked with returning soldiers to help them cope with post-traumatic stress disorder.

Kyle died on Saturday at a firing range in Glen Rose, Texas, while helping a soldier recovering from the condition, an ABC affiliate in Dallas, WFAA-TV, reported. A neighbour of Kyle was also killed.

A suspect has been arrested, and was identified as 25-year-old Eddie Routh. WFAA-TV quoted investigators as saying Routh was a former Marine who was believed to suffer from PTSD.

Kyle served four tours of duty in Iraq from 1999 to 2009, and received numerous honours.

He wrote a best-selling book called American Sniper. In it, he said his record as a sniper prompted Iraqi insurgents to put a price on his head.