At least 27 people died in Nepal on Friday when a tour bus fell into a gorge and went into the Marsyangdi River in the central district of Tanahun.

The bus, carrying tourists from Maharashtra State in the center-west of India, was en route to Nepal’s capital, Kathmandu, from Pokhara, a popular tourist destination. Nepal gets a lot of Indian tourists, mostly families who arrive by road to visit major Hindu temples.

The cause of the accident was not immediately clear.

Birendra Bahadur Shahi, a superintendent of police in Tanahun, said 16 others were injured in the crash. According to hospital reports, many of the injured were in serious condition. Mr. Shahi said they had been airlifted to Kathmandu for treatment.

The difficulty of the local terrain hampered rescue efforts, officials said. It took rescuers seven hours to lift the injured and the dead using ropes.

Nepal’s prime minister, K.P. Sharma Oli, said he was “deeply saddened” by the accident. On Saturday, India sent a government minister, Raksha Khadse, to Kathmandu to help with the treatment of the injured and the return of the dead.

Nepal has long struggled with road safety in its difficult, mountainous terrain. Roads are often narrow, and large parts of the country remain hard to reach.

Last month, a landslide sent two moving buses into the Trishuli River, killing more than 60 people. Between April 2022 and April 2023, there were more than 2,300 traffic fatalities.

The prevalence of such accidents, as well as a longstanding problem with aviation safety, endangers not only Nepal’s people, but also an important source of revenue in a poor nation: the tourism sector.

“Bad news spreads faster than good news,” said Babar Jung Gurung, a tourism entrepreneur in Pokhara.