Erath County Sheriff Tommy Bryant said Chris Kyle, a 38-year-old retired SEAL sniper with the most confirmed kills and the author of the book "American Sniper," his neighbor Chad Littlefield, 35, of Midlothian and ex-Marine Eddie Ray Routh, 25, had arrived at the Rough Creek Lodge and Resort near Glen Rose about 3:15 p.m. Saturday. Less than 2 hours later Kyle and Littlefield were found dead by a hunting guide and Routh was on the run in Kyle's Ford pickup truck, The Dallas Morning News reported.
Police went to Routh's home in Lancaster, where they spotted Kyle's truck. Routh fled in the pickup again, but was apprehended near Interstate 35 shortly after 8:30 p.m.
The Forth Worth Star-Telegram reported Kyle and Littlefield were shot multiple times and a semiautomatic handgun found Routh's home may have been the weapon used to kill them.
WFAA-TV, Dallas, reported the men were shot in the back.
"There were no witnesses. No one heard any type of an argument," Bryant said.
The sheriff said Routh's mother may have contacted Kyle to "help her son," an Iraq War veteran, though he could not confirm whether Routh was on medication or was diagnosed with Post Traumatic Stress Syndrome, the Morning News said.
"We have an idea that that's why they were at the range, for some kind of therapy that Mr. Kyle assists people with," Bryant said.
Routh was arraigned on two counts of capital murder and remanded to the Erath County jail in lieu of $3 million bail, Officer Kyle Roberts said.
Bryant told the Star-Telegram investigators had not determined a motive for the shootings.
"Not a clue, absolutely no idea," he said.
Kyle, who served in Iraq, was awarded two Silver Stars, five Bronze Stars with Valor and two Navy and Marine Corps Achievement Medals, the Star-Telegram said.
He was credited with more than 150 kills during his tours of Iraq and Afghanistan, with one sniper shot having hit its mark from 1.2 miles away.
Notable deaths of 2014 [PHOTOS]