MEXICO CITY, Mexico (CNN) -- The driver of a truck that collided with a bus in northeast Mexico, killing 12 people including 11 passengers from the United States and Canada, was intoxicated, a Mexican official said Tuesday.
Emergency workers wheel a crash victim on a gurney after Monday's bus crash in Mexico.
The tractor-trailer's 21-year-old driver was among those hospitalized after Monday's crash near Monterrey, Mexico, said Segismundo Doguin Martinez, a police official in the Mexican state of Coahuila.
The driver of the bus was among those killed, and 15 bus passengers were injured.
The Senda Express bus, operated by Grupo Senda, had been traveling from McAllen, Texas, carrying tourists to Zacatecas in central Mexico.
Eight of those who died were from the United States, three were from Canada and one, the bus driver, was from Mexico, Doguin said. Watch rescuers work at scene of deadly crash »
The survivors, most of them in grave condition, were taken to the Christus Muguerza Hospital and the Clinica La Concepcion, the Mexican official said.
"They are in a delicate state but out of danger," Doguin said.
El Milenio newspaper reported on its Web site that eight of the injured are from the United States, four are from Canada and three from Mexico. Seven of the injured Americans are from Texas and one is from Iowa, the newspaper said.
El Norte newspaper's Web site and El Porvenir said the dead and injured included tourists.
Among those killed in the crash was 73-year-old Ronald Christy, said his daughter, Pam Fordyce.
Christy's wife, Margaret Christy, was in critical condition in a Mexican hospital, Fordyce said.
"He was doing exactly what he loved -- traveling," Fordyce, of Altoona, Iowa, told CNN by telephone Tuesday. "He was right where he would want to be, on a bus."
She said the couple wintered in Texas and lived in West Liberty, Iowa, in the summer.
The U.S. consulate called her at 1:30 a.m. Tuesday to tell her that her father had been killed, Fordyce said, and then followed up with an e-mail with photographs of the crash.
"I didn't even know he was on a bus," she said. "I guess I could believe [the consulate] when I talked to my brother" who knew the couple was traveling, she said. "Until then you don't want to believe anything."
Doguin, the Mexican official, said the accident occurred when a truck driver went off the road and then overcorrected and swerved into oncoming traffic, hitting the bus.
Video of the scene from CNN affiliate TV Azteca 13 showed the left side of the bus sheared off and the semi's cab completely flattened.
Rescue efforts took five hours, TV Azteca 13 reported.
The U.S. consulate in Monterrey will not release the names of the dead or injured until all family members have been notified, said consulate spokesman Todd Huizinga.
"On Monday evening, staff from the consulate in Monterrey went to the Christus Muguerza Hospital to offer assistance to some of the injured who were brought there after the crash," Huizinga said. "The consulate expects to have more detail in the coming hours."
The truck driver was injured and is being held by authorities at a hospital, Doguin said.
The Web site for Grupo Senda says the company started in Linares, Mexico, more than 75 years ago. It provides bus service to 15 Mexican states and the Texas Valley, the site says.
Elizabeth Suarez, director of the McAllen Central Bus Station, where the bus trip originated, issued a statement saying, "We are very saddened by the news this morning. We offer our condolences to the families. The city of McAllen is the landlord of the bus terminal facility in McAllen. Grupo Senda is our tenant."
CNN's Melanie Whitley, Taylor Gandossy, Tess Eastment and Monica Trevino contributed to this report from Atlanta, Georgia.