A civil guard surveys the wreckage of a bus crash which left at least four people dead in Aviles, Spain, September 3, 2018. Image Credit: Reuters

Madrid: Five people died and 20 others were injured Monday when a bus crashed into the pillar of a viaduct in northern Spain, authorities said.

The accident took place in Aviles in the Asturias region, a spokeswoman for emergency services told AFP.

"Five people have died," a spokesman for the central government's representative office in Asturias added - all of them passengers.

Among the 20 injured was the driver, who had to have a limb amputated, the spokesman said.

Photos published in local media showed the front of the bus split in half by the pillar.

The bus was travelling on a highway at the base of the viaduct when the accident happened, the causes of which are still unknown.

It is the worst bus crash since March 2016, when 13 foreign students, most of them from Italy, died in a bus accident in the northeastern region of Catalonia.