Rescuers are searching for more than 60 missing people in Nepal after a massive landslide swept two buses into a river. Some spoke of their terrifying ordeal, with one saying he was "thrown out of the window of the bus into the river". Only three people appeared to have survived the accident, which took place in the early hours of Friday. Authorities said the landslide had been triggered by heavy rains. Nepal, along with other parts of South Asia, is in the midst of the monsoon season and has seen heavy rainfall in recent weeks, triggering floods and landslides that have affected millions. The accident took place at 03:30 local time (21:45 GMT Thursday) on Friday in Chitwan along the Narayanghat-Mugling highway, about 100km (60 miles) from the capital Kathmandu. Survivor Nandan Das told the BBC"s Nepali Service that the bus had been on the road for about an hour and a half when it "started rolling down all of a sudden into the river... I felt like I was going to die". He said he managed to swim to safety even though it was "very dark at night... I found the river full of huge boulders and some foliage. "We were chanting the name of God and swam and swam and swam. God saved us. "I did not know if I was swimming out to the river or inward... but I came to the bank at last. Then I started climbing the slope." He said that he and another survivor reached the highway at the same time, and were shortly joined by a third person. They managed to get help from a driver, who called the police. Another survivor, Jogishwar Raya, described the bus as "trembling and overturning four or five times before plunging into the river". He said he managed to swim out of the bus, but his family members were still missing. "My son, daughter-in-law , grandson, and a granddaughter were on the same bus. Out of five family members, I was alone to survive; the rest vanished," he said. Nepal"s Prime Minister Pushpa Kamal Dahal has called for all government agencies to join in the search and rescue operation. Scores of people are estimated to have died this monsoon season, with key highways blocked and some bridges swept away by swollen rivers. Authorities have urged residents in the south-east of the country to be on alert as the Koshi river, which courses through Nepal and India, is flowing above the danger level. Nepal also often sees deadly crashes due to poorly maintained roads and reckless driving. — BBC