Updated

A private charter bus that skidded off a highway north of Dallas early Friday morning and killed 15 members of a Vietnamese church group was not licensed to operate.

Records show the bus operator, Iguala BusMex Incorporated from Houston, has not been approved for operation with the Federal Motor Carrier Safety Administration and has an application pending.

The 12:45 a.m. crash sent at least 40 to hospitals, with at least six of them listed in critical condition. The charter bus was carrying a Vietnamese Catholic group to an annual pilgrimage.

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The company sought certification from the agency June 26, just weeks after it filed incorporation papers with the Texas Secretary of State. The company's owner and listed Houston address are the same as another bus company’s, Angel Tours Inc., which was forced by the FMCSA to take its vehicles off interstates on June 23 because of an unsatisfactory compliance review in May.

A man in the Houston building declined to identify himself and told The Associated Press he had no comment when asked if he was affiliated with the company or if it owned the bus involved in the crash.

Police said they weren't sure exactly how many were hurt in the accident, which happened on U.S. Highway 75 northbound in Sherman, about 64 miles north of Dallas. Fifty-five people were on the bus.

The bus ran off U.S. 75 and skidded along a guard rail spanning a bridge before siding off the highway on its side. The vehicle apparently blew a tire, but officials were still investigating the crumpled wreckage littered with luggage, shopping bags and scattered clothing.

"There were people deceased from the front of the bus to the back of the bus," Officer Zachary Flores, one of the first on the scene, told The Dallas Morning News.

The bus came to rest with half of its right side on the northbound lane of the freeway. Workers righted the wreckage and loaded it onto a flatbed truck.

The driver survived and was awake in stable condition and talking with investigators, Sherman Police Lt. Steve Ayers told reporters Friday.

He didn't release the driver's name and said police do not believe he fell asleep at the wheel.

"It would be premature to say exactly what may have happened," Ayers said. "We will treat it as a crime scene."

A blown-out tire on the bus, operated by Angel Tours, contributed to the wreck, Ayers said.

Ayers said those on the bus were Vietnamese Catholics on their way to a church event in Missouri. The group left from Houston.

Twelve were confirmed dead at the scene, and one died later at the hospital, Sherman Lt. Robert Fair told reporters. John Peter Smith Hospital confirmed another individual died from injuries sustained in the accident shortly after 1 p.m.

Many of the injured were being rushed by helicopters and ambulances to North Texas hospitals, including Dallas, Allen, Sherman, Denison and Durant, Okla.

“We’ve got ambulances and helicopters from all over the county,” Fair told the Morning News.

A spokeswoman at Wilson N. Jones Medical Center in Sherman said it was treating 17 patients.

"I saw crushing wounds," said Fire Chief Jeff Jones, "but there were very few walking wounded."

Two males and two females taken to Parkland Memorial Hospital in Dallas were reported to be in critical condition. Methodist and Baylor in Dallas also had two patients each transported to their hospitals, the Morning News reported.

A spokeswoman for a Sherman hospital where many of the injured were being treated told local media the passengers were from a Houston-area church on their way to a mission trip in Missouri. Houston Vietnamese Martyr Church chartered the bus, but the bus was carrying people from various churches, the source said.

The Herald Democrat reported that the victims were Vietnamese, and at least four translators were brought to the scene.

"Please pray for us," said Holly Nguyen, 38, a church member who was following behind the bus in a car but didn't see the wreck. She was anxiously waiting for word on whether her father, who was on the bus, was dead or injured.

It was unclear if weather played a role in the accident. A National Weather Service meteorologist said there was some light rain in the area around midnight.

Many of those on the bus were from the Vietnamese Martyrs Church of Houston and were on their way to a religious festival in Carthage, Mo.

Tinh Trinh, a church member for 20 years, said he was waiting to hear how one of his wife's friends was doing.

"I myself cried this morning when I heard the news," said Trinh, one of only a few people at the large brick church early Friday.

The Marian Days pilgrimage, which started in the late 1970s in southwest Missouri, attracts thousands of Catholic Vietnamese Americans each year. Many attend a large outdoor mass each day while enjoying entertainment and camping throughout the city at night.

The northbound lanes of the interstate were shut down and traffic was being diverted, Fair said.

The accident happened less than a mile from the spot where a trucker crossed the median and killed 10 people five years ago.

It was the deadliest bus crash since 2004, when 15 people were killed on a bus that crashed in eastern Arkansas as it headed to Mississippi casinos. In 2005 near Dallas, 23 people were killed in series of explosions on a bus carrying nursing home residents away from Hurricane Rita.

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The Associated Press contributed to this report.