College Station, Texas ? Texas A&M football player Brandon Fails died from a blood clot in his lungs that resulted from a leg injury, the Travis County Medical Examiner’s Office said Tuesday.

The 18-year-old defensive lineman died Monday after collapsing as he was leaving his dorm room.

He had complained of problems breathing and later died at a hospital in Bryan.

The blood clot that traveled to his lungs was initially caused by an injury to the leg, officials with the Travis County Medical Examiner’s Office said.

The 6-foot-1, 307-pound Fails hurt his right knee in practice and had knee surgery Oct. 22.

The Travis County Medical Examiner’s office, which contracts with Brazos County, made the initial ruling about the massive pulmonary thromboembolism after conducting an autopsy Tuesday.

“It’s a condition you can anticipate (after) surgeries that requires you to be immobilized for extended periods of time,” team physician Jesse Parr said. “But he was not immobilized. He was up and able, and on crutches pretty quickly.”

Parr said there would be no warning signs for such a clot.

“What happens is just what we saw – a catastrophic, sudden event,” he said. “Life can be so good on Sunday night visiting with his parents, but then things can suddenly deteriorate. It’s one of these things that you don’t have any control over.”

Pulmonary embolism occurs when a blood clot, or a portion of it, breaks free and circulates through the bloodstream to the lungs. It can become trapped in the arteries there.

If the clot restricts blood flow to a large section of the lungs, sudden death can result.

The full autopsy report wasn’t expected to be released until today.

Dr. Samuel Z. Goldhaber, an associate professor of medicine at the Harvard Medical School and the founder of Brigham and Women’s Hospital Thromboembolism Service in Boston, said in a story in today’s Austin American-Statesman said any clotting that would occur in the calf after the kind of knee surgery Fails had would be minor and “rarely would they break off and go to the lungs.”

Like all freshman players at A&M, Fails was given a complete physical before reporting for football practices Aug. 5.

Fails played in four games this season before undergoing the surgery. He would have been a starting prospect for next season.

Fails was voted Class 5A Defensive Player of the Year by Associated Press Sports Editors last season. He was a first-team All-State selection by the APSE and the Texas Sports Writers Association.