NEW DELHI—Rescuers worked Sunday morning to find survivors of a powerful 7.8-magnitude earthquake that killed hundreds of people in and around Nepal’s capital, Katmandu. (Further news: Nepal hit by fresh earthquakes on May 12).

The country’s police put the death toll at almost 1,900, with more than 4,500 injured, as emergency personnel fanned out across the city and its surrounding valley, home to about 2.5 million people.

“There...