Witnesses say the woman who was killed after being thrown from a roller coaster in Texas was concerned that her lap restraint didn't work. NBC's Charles Hadlock reports.

The investigation of the death of a woman on a roller coaster at Six Flags Over Texas will be led by Six Flags itself, because there's no state or federal agency responsible for enforcing the safety of amusement parks.

Rosy Ayala-Goana of Dallas died Friday night when she fell from the Texas Giant, which is billed as the world's steepest wooden roller coaster.

Six Flags initially said in a statement that it was "working with authorities" to figure out what happened. But it later had to admit that it was running the investigation itself because there are no authorities to work with.

No federal agency has legal authority to enforce safety standards. And Texas is one of at least 17 states that have no agency responsible for inspecting amusement park rides, according to NBC News' survey of state codes in all 50 states.

While he was previously in the House, Sen. Ed Markey, D-Mass., introduced legislation every congressional session to establish federal regulation of amusement park rides beginning in 1999. But the measure never passed.

Markey renewed his call Sunday for federal regulation of "roller coasters that hurtle riders at extreme speeds along precipitous drops."

"A baby stroller is subject to tougher federal regulation than a roller coaster carrying a child in excess of 100 miles per hour," Markey said in a statement. "This is a mistake."

The Texas Giant, a 14-story-high, 4,900-feet-long roller coaster that is among the premier attractions at the park in Arlington, Texas, remains closed until Six Flags concludes its investigation, a park spokeswoman said. The park gave no timetable for reporting any information.

Nadine Kelley, who had been waiting in line for the ride Friday night, told NBC 5 of Dallas that riders who were sitting behind the woman said that "right when they came down off the first bump and hit that first turn, she flew out."

The woman was accompanied by two children, who were "hysterical," Kelley said. "They were saying that their mother flew out of the car."

"It was sad. It was very sad," she said. "We kept telling them to let them out because they were hysterical. The daughter and the son said, 'We have to go get my mom. We have to go get my mom.' We were kind of in disbelief, and we just said a prayer for her."

Alfred Cannon, Ayala-Goana's next-door neighbor, said Ayala-Goana was "an incredible mother to those kids."

NBCDFW: Neighbors recall woman who died on Six Flags coaster

Texas: Safety certificate 'not an endorsement' of safety

The Texas Giant is what's called a "super hybrid" — a roller coaster with traditional wooden components that rides on steel tracks.

"This track allows us to do much more with a wooden structure: steeper drops, steeper banks," Fred Grubb, president of Rocky Mountain Construction of Hayden, Idaho, said after his company rebuilt the ride two years ago.

The rebuilding deepened the ride's first drop to 79 degrees and banked several of its turns beyond 95 degrees, with one reaching 115 degrees, Grubb told Funworld, the magazine of the International Association for Amusement Parks and Attractions.

An independent inspection of the new ride would have been conducted by the Texas Insurance Department. But the department won't be part of the death investigation because the park's insurance isn't in question.

That's the case even though the Amusement Safety Organization, based in Montecito, Calif., had previously recorded four "significant injuries" on the ride this year, after having recorded seven last year. Nearly all were for whiplash-like neck injuries, it said.

Meanwhile, federal oversight and statistics on amusement park safety are almost nonexistent.

The U.S. Consumer Product Safety Commission and the National Safety Council both cite amusement park safety standards set by the American Society for Testing and Materials, but those standards are voluntary.

In Texas, the Insurance Department is responsible for setting regulations for amusement park rides. It requires an annual safety inspection certifying that ride meets ASTM standards. Texas law specifies that the inspection must be carried out by an inspector hired by the insurance company — not by any government authority.

To drive home the point that Texas isn't responsible for the safety of any roller coaster, the Insurance Department states: "Recognition by the Department that the amusement ride has satisfied these standards is not an endorsement by the Department or a statement regarding the safe operation of the amusement ride."

"There's absolutely no federal oversight, no state investigative oversight or any local investigative oversight," Ken Martin, an independent inspector and consultant on amusement park rides from Richmond, Va., told NBC News.

"It sounds like the fox guarding the henhouse to me," Martin said.

As of December, eight states required no permits or inspections for amusement park rides, according to a survey of state codes in all 50 states by NBC News:

Alabama

Mississippi

Montana

South Dakota

Utah

Vermont

West Virginia

Wyoming

In addition to Texas, six states accepted inspections from park-employed or -contracted inspectors or park insurance companies:

Florida doesn't inspect permanent facilities that employ 1,000 or more full-time employees and maintain their own safety inspectors.

Minnesota allows inspections by inspectors contracted by the park or by the State Agricultural Society.

Charles Hadlock of NBC News contributed to this report.

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