(CNN) -- A violent crash on a dirt track in New Jersey has claimed the life of race car driver Jason Leffler, a NASCAR veteran lauded by fellow racers as a fierce and versatile competitor.

Leffler, 37, died Wednesday, a little more than three months after returning to the world of short-track open-wheel racing after focusing on NASCAR circuits for more than a decade, according to his website.

"Sitting here in disbelief. ... All I can think about is Charlie," NASCAR racer Elliott Sadler said, referring to Leffler's 5-year-old son.

Leffler's death at Bridgeport Speedway in Swedesboro, New Jersey, came during a qualifying race during the Night of Wings event, a 25-lap race for sprint cars equipped with stabilizing wings.

Sprint cars are high-powered cars that usually run on dirt or paved oval tracks.

Leffler was on the fourth turn of the preliminary heat when his car left the banked dirt track and flipped several times down the front straightaway, the South Jersey Times newspaper reported, citing witnesses.

He had to be pulled from the vehicle, the newspaper said.

"NASCAR extends its thoughts, prayers and deepest sympathies to the family of Jason Leffler who passed away earlier this evening," NASCAR said Wednesday in a statement. "For more than a decade, Jason was a fierce competitor in our sport and he will be missed."

Condolences poured in from fellow drivers.

"Lost a good guy tonight in Jason Leffler. Prayers with your family!" racer Bobby Labonte said in a Twitter post.

"My thoughts and prayers are with Jason's family and friends," driver Jeff Burton posted. "Breaks my heart thinking of his little boy."

Leffler began racing when was 12 years old, according to his website, and went on to win four U.S. Auto Club racing championships -- including three back-to-back championships from 1997 to 1999 -- and a place in the National Midget Auto Racing Hall of Fame.

In 2000, he finished 17th in the Indianapolis 500.

He switched his racing focus that same year to NASCAR's Nationwide Series and later to the Camping World Truck Series in 2002, according to his website.

The Long Beach, California, native won two Nationwide Series races and finished in the top 10 in points for six consecutive years, according to his website.

He decided to return to dirt racing for 2013, planning to compete in up to 65 sprint car races.

"I've got a lot of learning to do," he was quoted as saying on his website in March. "It's cool to be able to race 3 times a week and figure things out."

Sprint car racing can be a dangerous sport, and accidents are not infrequent.

A 22-year-old driver died three weeks ago in a crash at Bloomington Speedway in Monroe County, Ind., CNN affiliate WTHR reported.

In March, two spectators died when a car veered off-track at Marysville Raceway Park, outside Sacramento, Calif.

In that incident, a car hit two tractor tires, sending it airborne and striking two spectators, a 68-year-old man and a 14-year-old boy. The driver was uninjured.

In 2012, a 20-year-old driver died when his sprint car hit the wall at Calistoga Speedway in Napa County, California, according to the Napa Valley Register.

CNN's Michael Pearson contributed to this report.

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