ANKARA, Turkey — Cries of panic and horror filled the air as a 7.2-magnitude earthquake struck eastern Turkey, killing at least 138 people as buildings pancaked and crumpled into rubble.

Tens of thousands fled into the streets running, screaming or trying to reach relatives on cell phones as apartment and office buildings cracked or collapsed. As the full extent of the damage became clear, survivors dug in with shovels or even their bare hands, desperately trying to rescue the trapped and the injured.

“My wife and child are inside! My 4-month-old baby is inside!” CNN-Turk television showed one young man sobbing outside a collapsed building in Van, the provincial capital.

The hardest hit area was Ercis, an eastern city of 75,000 close to the Iranian border, which lies on one of Turkey’s most earthquake-prone zones. The bustling city of Van, about 55 miles to the south, also sustained substantial damage. Highways in the area caved in.

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 rubble, he said, without citing any estimates.

Up to 80 buildings collapsed in Ercis, including a dormitory and 10 buildings collapsed in Van, the Turkish Red Crescent said. The sheer number of collapsed buildings gave rise to fears that the death toll could rise substantially.

U.S. scientists recorded over 100 aftershocks in eastern Turkey within 10 hours of the quake, including one with a magnitude of 6.0. Residents in Van and Ercis lit campfires, preparing to spend the night outdoors while the Red Crescent began setting up tents in a stadium. Others sought shelter with relatives in nearby villages.

Rescue efforts went deep into the night under generator-powered floodlights.

Erdogan urged residents to stay away from damaged buildings and promised assistance to all survivors.

“We won’t leave anyone to fend for themselves in the cold of winter,” he said.

Around 1,275 rescue teams from 38 provinces were being sent to the region, officials said, and troops were also assisting search-and-rescue efforts.

In Ercis, heavy machinery halted and people were ordered to keep silent as rescuers tried to listen for possible survivors inside a seven-story building housing 28 families, NTV reported.

Some inmates escaped a prison in Van after one of its walls collapsed. TRT television said around 150 inmates had fled, but a prison official said the number was much smaller and many later returned.

Nazmi Gur, a legislator from Van, said his nephew’s funeral ceremony was cut short due to the quake and he rushed back to help.

“We managed to rescue a few people but I saw at least five bodies,” Gur told The Associated Press. “It was such a powerful temblor. It lasted for such a long time.”

“But now we have no electricity, there is no heating, everyone is outside in the cold,” he added.

Authorities had no information yet on remote villages but the provincial governor was touring the region by helicopter and the government sent in tents, field kitchens and blankets.

The earthquake also shook buildings in neighboring Armenia and Iran.

In the Armenian capital of Yerevan, 100 miles from Ercis, people rushed into the streets in fear but no damage or injuries were reported. Armenia was the site of a devastating earthquake in 1988 that killed 25,000 people.

Sunday’s quake caused panic in several Iranian towns close to the Turkish border and caused cracks in buildings in the city of Chaldoran, Iranian state TV reported.

Leaders around the world conveyed their condolences and offered assistance.

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