(CNN) -- A former Navy SEAL known for claiming a record number of sniper killings in Iraq was killed Saturday at a gun range. The man charged in his death is a fellow veteran, a military official says.
Chris Kyle, 38, was the author of the best-selling "American Sniper: The autobiography of the most lethal sniper in U.S. military history." He and 35-year-old Chad Littlefield, also a veteran, were gunned down Saturday afternoon in Glen Rose, Texas, southwest of Fort Worth, the Texas Department of Public Safety said.
Police arrested suspect Eddie Ray Routh, 25, and served him with two felony warrants for capital murder.
The three men had apparently gone to the shooting range together, and no one else was around, Sheriff Tommy Bryant of Erath County told CNN on Sunday. The bodies were found at the range two hours later when someone came along.
Routh's family members could not be reached immediately for comment. No attorney has made a public statement on his behalf.
Routh, a former Marine, is believed to have left the service in 2010, a U.S. military official said Sunday. The official had no information on where Routh served or whether he took part in combat. The official spoke on condition of anonymity due to the sensitivity of the situation.
Routh's public records show he previously lived at Camp Lejeune in North Carolina.
Kyle, an outspoken advocate for war veterans, claimed more than 150 sniper killings during his time in Iraq, which he described as a record for any American. He said insurgents placed a bounty on his head and nicknamed him "the devil."
He leaves behind a wife and two children.
He appeared last year on the NBC reality show "Stars Earn Stripes," in which competitors took on missions based on military exercises.
Sheriff: Suspect fled in victims' truck
After the killings, Routh took off in Kyle's pickup truck, Bryant said.
Police went to arrest him at his home in Lancaster, about 75 miles away. They gathered outside the home and tried to persuade him to come out. But instead, Routh took off in a pickup truck, Lancaster police spokesman Lt. Kelly Hooten said. Authorities did not know immediately whether it was the same pickup truck.
There was a short pursuit, and police stopped Routh about four to six miles down the road, Hooten said.
He did not struggle with officers as they were arresting him, Bryant said.
Kyle and Littlefield were both involved with trying to help veterans who suffer from post-traumatic stress disorder. Bryant said he did not know immediately whether Routh suffered from PTSD.
At the range, investigators found 25 to 30 weapons, including handguns, long guns and AK-47s, Bryant said. Authorities do not yet know which weapon or weapons were used to kill.
Routh is unemployed, Bryant said.
A judge will decide whether to allow him bond.
'An American hero'
Kyle's friend Jason Kos said he was "a man of incredible character. He led by example. He always stopped to take time to talk to whoever was around him. Just incredibly humble, very funny as well."
Kyle helped establish the nonprofit Fitco Cares Foundation to help veterans battling PTSD get access to exercise equipment.
In a statement, the foundation described Kyle as an "American hero" and pledged to carry on his mission.
"What began as a plea for help from Chris looking for in-home fitness equipment for his brothers- and sisters-in-arms" struggling with PTSD turned into an organization that will continue after his death," Fitco Director Travis Cox said in a statement. "Chris died doing what he filled his heart with passion -- serving soldiers struggling with the fight to overcome PTSD. His service, life and premature death will never be in vain. May God watch over his family and all those who considered Chris a true friend."
Littlefield, also a veteran working to help people with PTSD, also leaves behind a wife and children, Cox said.
Kyle fought against weapons bans
Kyle served four combat tours in Iraq and received two Silver Stars, among other commendations.
He left the Navy in 2009.
He recently spoke out against weapons bans. In a video interview with guns.com, Kyle accused President Barack Obama of being "against the Second Amendment."
The founding fathers "had the same weapons the military did," he said. "We don't even have that today -- but don't try to take what I've already got."
'Not trying to glorify myself'
In an interview with Time magazine last year, Kyle defended his decision to write a book despite the secretive nature of the SEAL world.
"It's kind of frowned on," he told the magazine. "But I'm not trying to glorify myself. I didn't want to put the number of kills I had in there. I wanted to get it out about the sacrifices military families have to make."
He said that while killing did not come easy at first, he knew it meant saving lives.
"The first time, you're not even sure you can do it," he said in the interview. "But