HOUSTON — Tejano star Emilio Navaira did not have the proper license to drive his tour bus when he crashed it onto freeway median barrels on the West Loop early Sunday morning.

Navaira was thrown through the windshield and suffered a traumatic brain injury as a result. He was rushed to Memorial Hermann Hospital, where Dr. Alex Valadka and his team operated for two hours to remove a blood clot that was putting pressure on the singer’s brain.

Valadka said the singer sustained an acute subdermal hematoma in his brain, back fractures and other bruises.

“There is a chance he may not make it—everyone needs to understand that up front,” Valadka said Monday.

An officer at the scene of the accident Sunday said alcohol may have been a factor.

“I believe alcohol was involved – to what extent, I don’t know,” Bellaire Police Sgt. Daniel Kerr said.

Police took a blood sample to determine if Navaira was intoxicated, but the results wouldn’t be available for a few weeks.

Bellaire Assistant Police Chief Byron Holloway said Monday the crash was probably a result of driver error or a mechanical problem.

“I think the blood analysis might tell the tale,” Holloway said.

Holloway said it’s also possible the singer fell asleep at the wheel.

“Right now, the investigator handling the case hasn’t been really able to find anyone to say this happened or not happened,” he said.

Meanwhile, Navaira’s doctors said his battle for survival is an hour-to hour fight.

“Every patient behaves differently. You can’t say if he makes it ‘x’ number of hours he will be okay. As I told his family, we’re not going day by day. We’re going hour by hour,” Valadka said.

He added that the next 24 hours would be critical.

Though he arrived at the hospital in a natural coma, doctors decided to keep Navaira in a medically-induced coma to give his brain a chance to recover.

After the operation, Navaira became part of a study where doctors use hypothermia to treat the injury.

Valadka said recent studies have shown lowering a patient’s temperature helps keep the brain from swelling and prevents harmful biochemical reactions from occurring.

“Brain swelling is the biggest thing we’re worried about at this point,” Valadka said. “I think it is a good sign (that) so far the pressures in his brain have not risen and have been controlled. The longer we can keep doing that the better it is for him.”

Doctors said they hope to raise Navaira’s temperature Tuesday. To prevent shocking his system, his temperature will be brought up gradually over as much as 16 hours.

Valadka said people with injuries similar to Navaira’s usually have a 65- to 70-percent chance of survival.

“Any recovery will take a long time, you know this is not like you see on TV and movies—when people get hit in the head, wake up and go home the next day,” he said.

Several of Emilio’s relatives rushed to Houston after learning of the accident, including his wife, mother and sister.

Navaira’s agent said Monday he loved driving the tour bus.

“He would drive it in and drive it out,” Joe Casias said. “It was ordinary.”

Three other band members remained hospitalized Monday, said Casias, Navaira’s agent since 1989. According to Ben Taub Hospital, Ray Diaz-DeLeon is in fair condition. Rick Vega is in good condition, and Daniel Sandoval has been released from the hospital.

Three others, including Navaira’s brother Raul, were treated for minor injuries at area hospitals and released.

A seventh band member wasn’t on the bus because he was riding to San Antonio with his brother.

Navaira and the band were returning to their homes in the San Antonio area after performing at a Houston nightclub. They were scheduled to head to California for tour dates later this week.

“We ask his friends and fans for their prayers during this difficult time and we will release more information as it is available,” Casias said.

A mass and prayer vigil are planned for Emilio at 6:30 p.m. Monday at Immaculate Heart of Mary Church. That’s located at 7535 Ave K at 76th Street in Houston.

Three more vigils are planned for 7 p.m. Monday: One across the street from Memorial Hermann Hospital, another at Our Lady of Guadalupe Church at 514 Carlyle in Rosenberg and a third at the Alamodome in San Antonio.

Family friend DJ Jesse Rodriguez said he can only hope for the best for Navaira.

“Emilio has been described as the George Strait of Tejano music,” Rodriguez said. “I think if everyone can help and keep him in their prayers, everything will turn out alright.”

Navaira was born on Aug. 23, 1962 in San Antonio. He was a music major at Texas State University.

In the last 12 years, Navaira and Rio, his band, have won multiple awards and achieved significant success in both Mexico and the United States with Tejano and mainstream country music hits.

“Acuerdate” won the 2003 Grammy for best Tejano album.

Navaira has been a frequent performer at RodeoHouston, most recently in 2007. A group organized a boycott this year because no Tejano groups were invited to the rodeo for Go Tejano Day. But Casias said Navaira didn’t support the boycott because he believes the rodeo is “all about the kids” and the scholarship money raised.

Navaira has also had a few brushes with the law.

He was booked in San Antonio in 2000 for allegedly resisting arrest.

Police were called to a hotel lobby, where they said Navaira was arguing with a woman and appeared intoxicated and uncooperative. Navaira denied any wrongdoing.

That same year, he was arrested in San Antonio on DWI charges. He received probation and paid a fine as a result.

Navaira, who has been married twice, has five children ranging in age from 2 to 18.