CALGARY — At least three people were killed and two children injured following a  "horrific" crash on Hwy. 21 south of Three Hills, Alberta, RCMP said.

A southbound truck pulling a utility trailer collided head-on with a northbound truck pulling a horse trailer just after 6 p.m. Friday.

Both vehicles erupted into flames on impact and were destroyed.

The driver of the southbound truck was killed and two children riding inside were injured along with an adult passenger.

They were all members of a family from the nearby area, said Sgt. Patricia Neely.

At least two people in the northbound truck were killed, said Neely.

"This is one of the most horrific crashes I have ever attended," she said sombrely.

Two horses were in the trailer being pulled by the northbound truck.

One was killed and the other survived.

Neely said speed and alcohol were not factors in the crash and police are looking at the possibility of mechanical error being the cause.

The crash happened in a rural area south of Three Hills, about 135 km northeast of Calgary.