A 7.2-magnitude earthquake struck eastern Turkey Sunday, killing at least 138 people as buildings crumpled into rubble. The death toll was expected to rise as rescuers sifted through the rubble and reached outlying villages.

The bustling city of Van sustained substantial damage. About 55 miles (90 kilometers) to the north, Ercis, a city of 75,000 close to the Iranian border and in one of Turkey's most earthquake-prone zones, was also badly hit.

Prime Minister Recep Tayyip Erdogan said at least 93 people were killed in Van, 45 others died in Ercis and about 350 were injured. Several people were still trapped under the rubble, he said, without citing any estimates.

Residents in Van and Ercis lit campfires, preparing to spend the night outdoors. Rescue efforts went deep into the night under generator-powered floodlights.

We stand shoulder to shoulder with our Turkish ally in this difficult time, and are ready to assist, U.S. President Barack Obama said.

Check out some photos of the scene.