Nepali Information Minister Minendra Rijal said there had been "massive damage" at the epicentre, from where little information is emerging.
A national police spokesman told the BBC that 970 people had died in the quake, and that more than 1,700 had been injured. At least 539 people were killed in the Kathmandu valley, he added.
Breaking News: 7.5 magnitude earthquake has struck in Kathmandu and all other parts of Nepal. According to U.S. Geological Survey, earthquake occurred less than 50 miles from the capital city Katmandu.
Watch Exclusive footage from Nepal television of powerful 7.5 magnitude earthquake. "We need support from the various international agencies which are more knowledgeable and equipped to handle the kind of emergency we face now," Information Minister Minendra Rijal.
