The State Seismological Bureau (SSB) will send a team of 180 people to the site of today's major earthquake in Wenchuan County in southwest China's Sichuan Province for disaster relief.

Zhang Hongwei, spokesman for the SSB, said the bureau has launched a "top-level emergency contingency plan" that includes the team, which will gauge the impact on life and property in the county and help with relief work. So far, four people have been reported killed by the quake.

No time was specified for the team's departure.

A quake measuring 7.8 on the Richter scale jolted Wenchuan at 2:28 p.m. today, the bureau said. The epicenter of the quake was located 31.0 degrees north latitude and 103.4 degrees east longitude.

Tremors were also reported in Ningxia, Qinghai, Gansu, Shanxi, Shaanxi, Shandong, Yunnan, Hunan and Hubei Provinces and the Shanghai and Chongqing Municipalities, the SSB said.