A truck carrying explosives collided with another vehicle in northern Mexico and blew up, killing at least 34 people.
Authorities said the two vehicles crashed into each other Sunday evening on a busy highway, drawing a crowd of curious onlookers as well as a small army of police, soldiers, emergency officials and journalists.
Shortly after the crowd arrived, the wreckage caught fire, and the explosives blew up, sending a ball of fire into the sky that consumed nearby cars and left a 3-by-15-meter (10-by-40 foot) crater in the concrete, said Maximo Alberto Neri Lopez, a federal police official.
He initially reported 37 dead, but lowered that number after a more thorough count found that some bodies, difficult to identify, were counted twice. He also said more than 150 people were injured.
The force of the explosion blew out the windows of a passenger bus half a kilometer (a quarter of a mile) away.
The dead included three newspaper reporters from the nearby city of Monclova, said Luis Horacio de Hoyos of the Coahuila state Attorney General's Office.
It was unclear if the explosive truck's driver was among those dead. Early reports said he might have fled the scene.
The truck was carrying cargo from an Orica Ltd. explosives plant in nearby Monclova, said a federal police officer who wasn't authorized to give his name.
A woman who answered the phone at Orica's offices in Monclova said all company officials were at a meeting, and she could not comment. The Australia-based company is the world's largest explosives maker, with operations in 50 countries.
Monday's explosion, just a few hours south of the Texas border, comes amid an angry cross-border debate about the safety of Mexican trucks.
A new North American Free Trade Agreement program implemented over the weekend allows Mexican trucks that have received prior approval to cross into the U.S. and carry cargo throughout the country. Before, Mexican trucks were limited to a 25-mile (40-kilometer) section of the border. Many in the U.S. fought the change, arguing that Mexican trucks are unsafe.
Randy Grider, editor of Truckers News magazine, however, said Mexican trucks with hazardous materials aren't included in the new program.
"I think it would be a very long time before the border would open to hazardous loads," he said.
President Felipe Calderon said the federal government would work with local authorities in the tragedy's aftermath.
"I want to send my heartfelt condolences to the families of those who lost their lives in this horrible accident," he said in New Delhi, India, where he was attending the inauguration of a museum exposition.
Coahuila state has a large mining industry, most of it in coal.