A landslide has swept two passenger buses carrying more than 50 people into a swollen river in central Nepal.

Continuous rain and more landslides are making rescue efforts difficult after the incident in the Trishuli River.

Three survivors apparently swam to safety, but rescuers have not found any trace of the buses, which likely were submerged and swept downstream.

Nepal’s rivers generally are fast-flowing due to the mountainous terrain. Heavy monsoon downpours in the past few days have swollen the waterways and turned their waters murky brown, making it even more difficult to see the wreckage.

Home minister Rabi Lamichhane told parliament 51 passengers were missing more than 500 rescue personnel have been assigned to the search operation.

Elsewhere in the country, 17 people have died and three more people were injured due to landslides in different districts in the past 24 hours, he said.

The buses were on the key highway connecting the capital to southern parts of Nepal when they were swept away near Simaltal, about 75 miles west of Kathmandu.

More landslides blocked routes to the area in several places, government administrator Khima Nanada Bhusal said.

Additional rescuers and security forces were sent to help with the rescue efforts. Police and army personnel were searching using rubber rafts. Divers with scuba gear were also dispatched, according the Chitwan district police.

The three survivors were being treated in the hospital, the official said, adding that they reportedly jumped out of the bus and swam to the banks, where locals found them and took them to a nearby hospital.

A third bus was hit by another landslide on Friday morning a short distance away on the same highway. The driver was killed but it was not clear if there were any other casualties.

Nepal’s Prime Minister Pushpa Kamal Dahal said he was saddened by the news and expressed concern over recent flooding and landslides. He added that several government agencies were searching for the missing, in a post on the social media platform X.

On Thursday night, a landslide buried a hut and killed a family of seven near the resort town of Pokhara. The family were asleep when the landslide crushed their hut and damaged three more houses nearby.

Monsoon season brings heavy rains to Nepal from June to September, often triggering landslides in the mountainous Himalayan country.

Meanwhile, the government has also imposed a ban on passengers buses travelling at night in the areas where weather warnings have been issued, according to the Home Ministry.