Nepal says it is intensifying efforts to free hundreds of people trapped inside tunnels at hydropower projects, including the Trishuli-3A site, following Wednesday's flash floods, BBC reported. 

Crews - including experts from China and India - have been attempting to make contact but have so far received no response from inside the tunnel, officials say. 

Hundreds of the 2,500 people reported missing are believed to be employees of Nepal's hydropower sites, according to BBC. 

Wednesday's disaster has killed at least 794 people and more than 2,500 people are missing in Nepal, local officials say.