Story highlights The monster truck's driver says he passed out after hitting his head

Authorities say the monster truck killed eight spectators, including four children

12 people are listed in critical condition

A "monster truck" spun out of control and mowed down spectators at an event in northern Mexico, killing at least eight people, including four children, officials said.

Video of the incident at the Extremo Aeroshow in Chihuahua, Mexico, shows a massive red truck running over an obstacle on a dirt course and then swerving into the crowd as audience members scream.

The driver told authorities he passed out after hitting his head, a state prosecutor's spokesman said.

State Gov. Cesar Duarte told reporters Sunday that it was possible the truck's driver drank alcohol before Saturday's deadly crash.

Blood tests were conducted and prosecutors will determine who was responsible, Duarte said.

The crash injured dozens of people, Duarte said. On Sunday, 28 of them remained hospitalized -- 12 of whom were in critical condition.

The city's mayor, Marco Quezada Martinez, told the state-run Notimex news agency that he has ordered an investigation.

CNN has not been able to reach a lawyer representing the truck's driver.

Officials said the Extremo Aeroshow was suspended after the incident.

According to the event's website, the show included aerobatics, skydiving, hot air ballooning, motorcycles, fireworks and monster trucks.