INDIANAPOLIS — The motorcycle racing community mourned the death of a promising 13-year-old rider in a crash at Indianapolis Motor Speedway while defending the youth circuit that allows teens to drive vehicles that can top 120 mph.

Peter Lenz of Vancouver, Wash., fell off his bike during the warmup lap for Sunday's first race at Indianapolis and was run over by another motorcycle, driven by a 12-year-old. Medical workers immediately placed Lenz in a neck brace, put him on a stretcher and began chest compressions while taking him to a hospital.

Several hours later, he was pronounced dead.

The Marion County coroner's office said Lenz died from blunt force trauma. More details could be released Monday following an autopsy on the youngest driver or rider ever killed at the 101-year-old speedway.

"Peter passed away early this morning when he was apparently struck by another rider," read a posting on Lenz's Facebook page, which was signed "Dad."

"He passed doing what he loved and had his go fast face on as he pulled onto the track," the posting said. "The world lost one of its brightest lights today. God Bless Peter and the other rider can only hope to reach. Miss you kiddo."

Lenz rode the No. 45 bike, and his father was at the track Sunday.

It was the first death at the track since IndyCar driver Tony Renna was killed in testing in October 2003.

Lenz had emerged as one of America's youngest rising stars.

At age 11, he earned the "expert" license from the American Federation of Motorcyclists, and in March 2009, Lenz became the youngest rider ever to win an AFM race. This year, competing in the U.S. Grand Prix Racers Union series, Lenz had four wins, five podium finishes and was leading the MD250H classification in points.

The grown-up resume just didn't match his appearance. Listed at 4-foot-11 and 81 pounds, the baby-faced Lenz described his profession as "kid."

"Our hearts go out to the parents, family and friends of Peter Lenz," speedway CEO Jeff Belskus said in a statement. "Words cannot adequately express the sadness of our company and our employees about this tragic incident, and Peter is in our thoughts and prayers."

It wasn't the first time Lenz was involved in a serious crash.

A mechanical failure last season left Lenz with four broken bones and a severed radial nerve — all of which required surgery. By November, Lenz was healthy again.