About eight people have been killed and dozens injured at a show in Mexico after a modified pick-up known as a monster truck crashed into spectators.

 One child was said to be among the dead in the northern city of Chihuahua on Saturday evening.

The monster truck with 1.5m-high (5ft) wheels was performing a demolition stunt during an annual air show in Chihuahua, which involved crushing two cars beneath its huge tyres.

Eyewitness said that after the truck completed one pass, driving over the cars, and then turning for a second attempt, it accelerated much more quickly and landed heavily over the second car before veering off to the right and into the stand.

Paramedics helped evacuated those hurt. About 50 persons were treated in hospital.

A spokesman for the Chihuahua state prosecutors' office, Carlos Gonzalez, put the number of injured at about 80.

He said prosecutors were looking at the possibility that mechanical failure meant the driver was unable to disengage the accelerator.

But some witnesses said the driver may have lost control after hitting his head on the interior of the truck.

A call has gone out from local health services for blood donations.