LANZHOU -- Some houses have collapsed after a 6.2-magnitude earthquake jolted Jishishan county in Northwest China's Gansu province late Monday evening, but casualties are still being investigated, according to the provincial emergency management department.

Heads of the provincial Party committee and government are rushing to the quake-hit area.

Local health authorities said they are ready to provide emergency medical treatment.

An emergency response has been launched by the local emergency management and fire departments.

Jishishan county is located at the junction of Gansu and Qinghai provinces, approximately 200 km from the provincial capital of Lanzhou. Many areas in Gansu and Qinghai experienced strong tremors.

In Jishishan and Yongjing counties, many people were seen on the street after the earthquake.