BUENOS AIRES – At least 10 people were killed and 40 others injured in a crash involving a truck and two buses in Chubut, a province in southern Argentina, police said Tuesday.

The majority of the fatalities were border patrol officers aboard one of the buses involved in the accident on Highway 3 near Puerto Madryn, a popular Patagonian tourist destination located about 1,300 kilometers (808 miles) south of Buenos Aires.

“As of now, we have 10 people dead” and “the injured are being transported to the hospital in Madryn, local clinics and other hospitals and health centers,” Puerto Madryn fire department central station chief Marcelo Dopazo told the official Telam news agency.

Chubut Gov. Martin Buzzi has declared three days of mourning over the accident, whose cause is being investigated.

The border patrol officers had been deployed in the past few days to deal with the protests at the Cerro Dragon oil complex operated by Pan American Energy, Argentina’s second-largest oil producer, which is owned by British, Chinese and Argentine interests.

Officials are negotiating with the protesters. EFE