Iraq veteran and ex-US Navy seal Chris Kyle, known as the deadliest sniper in US history, has been shot dead on a Texas shooting range, reports say.
His body was found at Rough Creek Lodge range on Saturday along with that of his neighbour, Chad Littlefield.
Iraq war veteran Eddie Ray Routh, 25, has been charged with murdering both.
Mr Kyle, 38, wrote the 2012 bestseller American Sniper, about the psychology of a sniper, in which he said that he had killed more than 250 people.
He served four tours of duty in Iraq and was decorated for bravery.
The gunman opened fire at about 15:30 local time (21:30 GMT) on Saturday, then fled in a pick-up truck belonging to one of the victims, local media reported.
Erath County Sheriff Tommy Bryant said Mr Routh then travelled to his sister's home, telling her what had happened before leaving.
She called the police and Mr Routh was arrested near his home in Lancaster, Texas, more than 70 miles (110 km) from the scene of the shooting, several hours later.
Sheriff Bryant said the motive for the killings was unclear, and was unable to explain how the two men were shot.
Travis Cox, director of a non-profit-making organisation Mr Kyle had helped found, told the Associated Press news agency that Mr Routh was suffering from post-traumatic stress disorder and that Mr Kyle and Mr Littlefield were trying to help him.
Scott McEwen, who co-authored the book with Kyle, said: "It just comes as a shock and it's staggering to think that after all Chris has been through, that this is how he meets his end, because there are so many ways he could have been killed."
Mr Kyle, a former cowboy, is regarded as the most prolific sniper the US has ever seen.
Official Pentagon figures say he killed 160 people, but he estimated the total was 255.
According to army intelligence, he was nicknamed "The Devil" by Iraqi insurgents, who put a $20,000 (£13,000) bounty on his head.
He appeared to show little remorse for his victims.
"Every person I killed I strongly believe that they were bad," he told the BBC in an interview a year ago.
"When I do go face God there is going to be lots of things I will have to account for but killing any of those people is not one of them."