INDIANAPOLIS - IndyCar has launched its probe into the crash in which Dan Wheldon died, and hopes to have a preliminary report within weeks, the US open-wheel racing series said in a statement on Wednesday.

Wheldon, a 33-year-old English driver who won the famed Indianapolis 500 twice, died on Sunday when he was caught up in a stunning chain-reaction crash at Las Vegas Motor Speedway in what would have been IndyCar's season finale.

Fifteen cars were involved in the fiery melee on the 12th lap, after which the race was cancelled.

"The entire IndyCar family is saddened by Dan Wheldon's tragic death, and our thoughts continue to be, first and foremost, with Dan's wife, Susie, and his entire family at this incredibly difficult time," an IndyCar statement said.

"As part of our standard safety protocol, a full investigation has been launched by IndyCar, with assistance from individual members of various motorsports bodies," the statement said, but it clarified that neither the International Motoring Federation (FIA) nor the Automobile Competition Committee of the United States (ACCUS) - which serves as the interface between the FIA and US member clubs - was involved in an official capacity.

"We hope to have preliminary findings to report within the next several weeks. In the meantime, it would be inappropriate to comment further until the investigative team has had the opportunity to conclude its work," the statement said.

IndyCar vowed that the probe would seek to discover if speeds at the Las Vegas track were too high or if the field was too crowded.

Some drivers had predicted a chaotic race on the oval circuit at Las Vegas.

The circuit had been reconfigured to add "progressive banking" designed to increase side-by-side racing, which can be particularly dangerous in open-wheel races.

Sam Schmidt, a former driver and Las Vegas native who runs the team for which Wheldon ran his final two races, said the accident could have happened almost anywhere.

"It's similar to what we do at Texas - with a little more speed a few more cars - but I don't think the track's to blame," Schmidt said.

Jimmy Johnson, the five-time defending champion of the hugely popular NASCAR stock-car racing series, sparked a heated debate when he said after Wheldon's death that IndyCar races shouldn't be held on oval tracks, but instead only on road-style courses.

Johnson later said he was referring to high-banked ovals, which he believes are unsafe for open-wheel race cars.

While the discussions are sure to intensify, many drivers have said they just want to focus now on Wheldon, who leaves behind a wife and two small sons.

Colombia's Juan Pablo Montoya, a former Formula One star and Indianapolis 500 winner who now drives in NASCAR, was among them.

"I think people really have to forget about that," Montoya said. "Now with the social media and everything anybody's opinion really counts.

"And I think the only opinion that really matters right now is the one where we worry about Dan and his family. Let's let IndyCar deal with their problems."

Agence France-Presse