Authorities moved more than 45,000 people in earthquake-hit Tibet to shelters in a massive rescue operation near the foot of the Himalayas, as they wound down the search in a high-altitude environment where the odds of survival were always slim.

More than 120 people have been killed after a powerful earthquake struck a remote region of Tibet on Tuesday morning, with tremors felt across the Himalayas in neighboring Nepal, Bhutan and parts of northern India.

China recorded the magnitude as 6.8. The U.S. Geological Survey said it measured 7.1, with an epicenter some 50 miles northeast of Mount Everest.