Chinese President Hu Jintao led the charge Monday, ordering "all out efforts to help those affected" by the "major earthquake."
Chinese Premier Wen Jiabao is on his way to the affected area, to personally direct the rescue work.
The earthquake struck Monday afternoon, in Wenchuan County in southwestern Sichuan province. The epicenter was 90-kilometers away from the provincial capital, Chengdu.
Chongqing is a large municipality next to Sichuan province.
The vice-director of the Sichuan Earthquake Bureau, Deng Changwen, spoke to China Central TV by phone.
He says, because of the large earthquake, all communication to the disaster area has been cut off, exacerbating official attempts to determine the real situation.
Initial reports say at least four young students have been killed after the earthquake toppled two primary schools.
Chinese troops have been dispatched to help with disaster-relief work.
The powerful quake was felt as far away as Beijing, 1,500 kilometers to the north, as well as Thailand and Vietnam.
The hardest hit county, Wenchuan, has 111,000 people, with a large ethnic Tibetan population. Wenchuan county is also home to the Wolong Nature Reserve, China's leading research and breeding base for endangered giant pandas.