Regions of Myanmar, southern China, and northern Thailand early Monday morning, leaving dozens dead, hundreds injured, and numerous people trapped under the rubble.

The quake struck at 3:42 a.m. local time, with its epicenter in a mountainous area on the border between Myanmar and China’s Yunnan province, at a depth of approximately 10 kilometers, according to data from the U.S. Geological Survey (USGS). The quake was also strongly felt in the cities of Chiang Rai and Chiang Mai, Thailand, where mass evacuations were reported.

Myanmar, the worst-hit country to date, has declared a state of emergency in several regions after reporting at least 48 dead and more than 300 injured, with dozens missing. In the city of Lashio, buildings have completely collapsed, and rescue teams are working against the clock to find survivors in the rubble.

“We heard a loud noise, and suddenly everything started shaking. The walls cracked, and the ground moved like waves,” said Myo Thant, a resident of the affected area who managed to escape with his family before their house collapsed