Lima: At least 12 police officers were killed and a dozen were wounded in a remote Andean region in Peru when their bus skidded off an unpaved road and tumbled down a cliff, the government said on Tuesday.

The officers were headed to the highland province of Antabamba to provide security for talks between government officials and residents who have staged protests to demand a paved highway in the region.

Two helicopters retrieved the wounded from the bottom of the cliff, the Interior Ministry said. Four officers were in critical condition in the southern Peruvian city of Cusco, said regional health director Jorge Ponce.

Road accidents kill dozens of people every year high in the Peruvian Andes, where driving is rarely policed and most routes curve sharply but are unpaved.

President Pedro Pablo Kuczynski, five months into his five-year term, has promised to bring sorely needed infrastructure to poor rural regions as part of his promise to reduce inequality and bolster domestic demand.

‘Today’s a day of mourning because 13 police officers have died unnecessarily in a highway in Andes,’ Kuczynski said during a ceremony for graduating police officers.

The Interior Ministry said in a statement earlier on Tuesday that 12 had died and that it was investigating the incident.