Updated

Charges could be filed in the weekend drag-racing accident in Tennessee that killed six young car show spectators and left more than a dozen others injured, officials said Monday.

The Tennessee Highway Patrol told reporters at a news conference that investigators were still reconstructing the accident scene, interviewing witnesses and gathering all the evidence, and they haven't ruled out filing charges.

But it was too early to determine whether charges definitely would be filed, what those charges would be and against whom they'd be brought, officials said. They described the accident scene as "complex" and said "significant resources have been brought in" to conduct a thorough investigation.

The community held an impromptu vigil Sunday night for the victims, the Highway Patrol said. Eighteen people who were hurt in the wreck still were being treated at area hospitals, according to authorities.

The six killed in Saturday's tragic crash — which happened when a race car at the annual charity event Cars for Kids suddenly spun out of control during a stunt and plowed into the crowd — were in their teens and early 20s, according to Tennessee Highway Patrol spokesman Mike Browning. There was no guard rail protecting spectators where the burnout stunt went awry.

The car was driven by Australian pro drag racer Troy Warren Critchley, who wasn't severely wounded in the crash.

Saturday's wreck injured at least 20 others, including a 5-year-old boy, who were taken to hospitals in Tennessee and Mississippi.

Cars for Kids has staged a charity car show for 18 years in the small town of Selmer, and the drivers always do crowd-pleasing burnouts — spinning the tires to make them heat up and smoke — at the end of the parade.

There never had been an accident until this weekend, when Critchley lost control of his car.

Critchley, an Australian drag racer based in Wylie, Texas, suffered minor injuries and was taken by car to a hospital, authorities said.

The Australian National Drag Racing Association offered condolences to the victims. CEO Tony Thornton said the car show was not a sanctioned drag-racing event and was a demonstration using drag cars that went horribly wrong.

Witnesses questioned the decision Sunday to let the driver speed down a highway with no guard rails, lined on both sides by hundreds of spectators.

"It ain't really safe to do anything with drag cars on a city street," according to 19-year-old Garett Moore, who said he was about 15 feet from the wreck but was uninjured. "They shouldn't have done it."

Amateur video of the crash, broadcast on WMC-TV in Memphis, showed the car's engine revving loudly before the vehicle sped down the highway. After a few hundred feet, the smoking car skidded off the road and into the crowd.

There was a short guard rail along part of the highway but not along the stretch where the crash occurred.

Nick Staples, who was at the event with his wife and three children, said he was standing 20 feet from where the car plowed into the audience.

"There should have been guard rails," Staples said. "But even if there had been, it wouldn't have mattered."

Mourners placed small votive candles, flowers, teddy bears and a ceramic angel at the crash site, along state Highway 64 near the intersection with Highway 45.

The Highway Patrol said Raven Griswell, 15, of Finger, and Sean Michael Driskill, 22, of Adamsville, died at the scene. Four others — Brook L. Pope, 20, of Selmer; Scarlett Replogle, 15, of Selmer; Kimberly A. Barfield, 17, of Adamsville; and Nicole Griswell, 19, of Selmer, died in hospitals.

Authorities closed the festival after the crash.

Cars for Kids holds several events throughout the nation and raises close to $200,000 annually for charities that help children in need, according to its Web site.

The charity was formed in 1990, two years after founder Larry Price's son, Chad, suffered a severe head injury in a bicycle accident. Price promised that if his son was saved from lifelong injuries, he would spend the rest of his life raising funds for disabled children, according to the Web site.

Price said he hoped to keep the charity going, but he wouldn't do any more burnouts on public streets.

FOX News' Catherine Donaldson-Evans and The Associated Press contributed to this report.