An earthquake killed at least 116 people in a mountainous area of northwestern China, officials and state media said Tuesday, crumpling buildings while residents slept inside and sending people rushing into a frigid night.

Rescuers were searching for survivors in rural Jishishan County in Gansu province, the epicenter of the quake, officials from Gansu said at a news conference Tuesday. They said the quake, which struck at 11:59 p.m. Monday, had killed 105 people in the province and injured nearly 400 others.

Eleven people in the city of Haidong in neighboring Qinghai province were also killed, according to the state-run Xinhua News Agency.