SHERMAN, Texas (AP) – An illegally operated charter bus carrying a Vietnamese-American Catholic group on a pilgrimage to an open-air religious festival blew a tire and skidded off a highway early Friday, killing at least 15 people and injuring more than 40, authorities say.

The bus, en route from Houston to Missouri with 55 people aboard, smashed into a guardrail and tipped over along the edge of the road at about 12:45 a.m., crushing one side of the vehicle and scattering luggage, clothes, a sandal and a blood-soaked pillow across the grass and pavement.

More than a dozen victims were reported in critical condition. Ten people were taken to the hospital by helicopter.

Passenger Leha Nguyen, 45, said people were dozing off aboard the bus when she heard a noise and screaming, and opened her eyes.

“Somebody was laying on my legs. A lady next to me, she had her arm crushed up. The lady who was on my left, a man was on top of her,” she said at a hospital. She said nobody had been wearing seatbelts, and people were strewn all over. A television had fallen on one person.

“I think I’m the luckiest one out of most people,” she said.

Most of the passengers were from the Vietnamese Martyrs Church and two other mostly Vietnamese congregations in Houston and were on their way to Carthage, Mo., for an annual festival honoring the Virgin Mary.

The Marian Days pilgrimage, begun in the late 1970s, attracts thousands of Catholics of Vietnamese descent and includes a large outdoor Mass each day, entertainment and camping at night.

“Please pray for us,” said Holly Nguyen, a 38-year-old church member who was following behind the bus in a car but did not see the wreck. She anxiously awaited word of her father, who was on the bus when it ran off the road about 65 miles north of Dallas, close to the Oklahoma line.

The bus operator, Iguala BusMex Inc. of Houston, had applied in June for a federal license to operate as a charter but was still awaiting approval, according to online records.

The company recently filed incorporation papers, listing the same owner and address as Angel Tours Inc., which was forced by federal regulators to take its vehicles out of interstate service June 23 after an unsatisfactory review, records show. Details of the review were not in the online records.

The tragedy was the nation’s deadliest bus crash since 2004, when 15 people were killed in a wreck in Arkansas on their way to Mississippi’s casinos. In 2005 near Dallas, 23 people were killed when a bus carrying nursing home residents away from Hurricane Rita caught fire while in bumper-to-bumper traffic.