BEIJING — A strong earthquake shook a high-altitude region of southwestern China and areas of Nepal on Tuesday, damaging hundreds of houses, littering streets with rubble and killing at least 126 people in Tibet. Many others were trapped as dozens of aftershocks shook the remote region.

More than 400 people trapped by a strong earthquake in the foothills of the Himalayas have been rescued, Chinese officials said, while over 30,000 residents have been relocated, as the search for survivors entered a second day on Wednesday.

An earthquake in the Tibet region of China on Tuesday killed no fewer than 53 people and collapsed many buildings. State media reported that tremors were