Tony Stewart won Saturday's NASCAR Nationwide Series season-opener at Daytona International Speedway after a horrific crash occurred on the frontstretch, which 28 race fans in the grandstands.

The multi-car accident occurred in the tri-oval when then-leader Regan Smith was hit from behind by Brad Keselowski, the 2012 Sprint Cup Series champion. Smith's car spun into the outside wall and then turned around, collecting several drivers who were running behind him in a tight pack. Rookie Kyle Larson flipped around and then sailed into the catchfence before coming back down on the track.

Larson's car tore a gaping hole in the catchfence, with the engine and one of the tires sheared off his No. 32 Chevrolet and lodged in the fencing.

During a press conference held almost three hours after the incident occurred, Daytona International Speedway Joie Chitwood confirmed the number of fans who were injured from flying debris. Fourteen of them were transported to nearby Halifax Health Medical Center as well as other hospitals in the Daytona Beach area. The remaining fans were treated at the racetrack's infield medical care center.

Chitwood did not reveal the conditions of those injured, but according to multiple reports, seven people were seriously hurt while two more were listed in critical condition.

None of the 12 drivers involved in the crash were injured though.

"There was obviously some intrusion into the fence, and fortunately with the way the events are equipped, there was plenty of emergency workers ready to go," NASCAR president Mike Helton said during an interview on ESPN's post-race coverage. "They all jumped on it pretty quickly.

"Right now, it's just a function of trying to determine what all damage is done. They're moving folks to care centers and taking some folks over to Halifax Medical Center."

Larson, a Japanese-American driver who made his first career Nationwide start, climbed out of his heavily damaged car on his own.

"I was getting pushed from behind, and by the time my spotter said, 'Lift," it was too late," Larson said. "I had some flames come in the cockpit. I was alright and could get out of the car quickly. It was definitely a big it."

Another big crash, involving 13 drivers, took place between turns one and two with five laps to go, forcing NASCAR to halt the race for 20 minutes due to track cleanup efforts. Michael Annett tagged Austin Dillon and spun him around, triggered the wreck.

Annett had to be transported to the hospital where he will remain overnight for further observation. According to a statement from his Richard Petty Motorsports team, Annett complained of pain in his chest and sternum. He was treated for bruising on his chest and underwent a CT scan.

The caution for that accident setup a two-lap shootout to the finish.

Smith, who had won the 2012 Nationwide season-finale at Homestead-Miami Speedway in his first start for JR Motorsports, held the lead for the final restart. After Smith was turned around, Stewart dove to the bottom of the track to avoid the incident. He crossed the finish line ahead of Sam Hornish Jr., who had pushed Stewart to the front during the last two laps.

"We've always known since racing started this is a dangerous sport," Stewart said during a non-celebratory affair in Daytona's Victory Lane.

Stewart has now won the Nationwide season-opener at Daytona a record-tying seven times, including five victories in the past six races. Dale Earnhardt also won this event seven times.

Rookie Alex Bowman finished third, followed by Dale Earnhardt Jr. and Parker Kligerman.

Brian Scott, Justin Allgaier, Eric McClure, Robert Richardson Jr. and Travis Pastrana completed the top-10.

Danica Patrick suffered engine failure in the early going and ended up finishing 36th. Patrick, who graduated from Nationwide to Sprint Cup full-time this season, landed a ride in a Turner Scott Motorsports entry for this event.

"It's unfortunate," said Patrick, who had led five laps. "We were having an awesome day, and it was really fun out there. It's fun to do these speedway races. My motivation was to go out there and win today."

Patrick will start on the pole for Sunday's Daytona 500. Last Sunday, she became the first woman to win a pole position for a race in NASCAR's premier series.