Nepal‘s Prime Minister K.P. Sharma Oli in a tweet said 25 people had been killed, and around 400 were injured.
The top bureaucrat of Bara district, where the storm hit, said the death toll may increase as rescuers were still trying to reach many of those affected.
Bara is located about 62 km (39 miles) south of Kathmandu and borders India’s eastern state of Bihar.
Pre-monsoon thunderstorms are common in Nepal during the spring season but are rarely of an intensity that causes high casualties.
(Production: Yubaraj Sharma, Sunil Kataria, Malgorzata Wojtunik)