Lima, Oct 26 : At least four people were killed and dozens injured after two passenger buses collided head-on in the southern Peruvian department of Cusco, authorities said. The accident occurred on Sunday at around 1:30 a.m. in Espinar province, the Superintendence of Ground Transportation of People, Cargo and Goods (Sutran) said in a statement. One of the buses was travelling the Cusco-Arequipa route and the other was going in the opposite direction when they collided head on, Xinhua news agency reported. Both bus operators were registered in the National System of Ground Transportation and have Compulsory Traffic Accident Insurance, according to Sutran. Cusco health authorities said regional hospital personnel were attending to the many injured. Radio Programas del Peru added that due to the high number of injured victims, the Espinar Fire Brigade requested backup from police and even local residents. Authorities said they have launched an investigation to determine the causes of the accident. /IANS