CHENGDU, June 18 (Xinhua) -- Twelve people died and another 135 were injured after a 6.0-magnitude earthquake hit southwest China's Sichuan Province on Monday night, the provincial bureau of emergency management said Tuesday.

The earthquake hit Changning County of Yibin at 10:55 p.m. Monday (Beijing Time), according to local authorities.

The epicenter, with a depth of 16 km, was monitored at 28.34 degrees north latitude and 104.90 degrees east longitude, according to the China Earthquake Networks Center.

Rescuers said nine people died in Changning and three in neighboring Gongxian County. Most of the deaths were caused by damaged houses.

The first round of search and rescue operations have been completed in the two counties, and no new casualties were found, according to Sichuan bureau of emergency management.

As of 11 a.m. Tuesday, the quake toppled down 73 houses and severely damaged 19 others. Nearly 4,500 people were evacuated in quake-hit areas. Direct economic loss totaled 10.82 million yuan (about 1.59 million U.S. dollars).

On Tuesday morning, 53 people were still receiving treatment in two hospitals in Changning. Among them, two are in critical conditions and six others are severely injured.

The Ministry of Emergency Management has activated an emergency response and sent a work team to the stricken areas to provide guidance in rescue and disaster relief.

The ministry and the National Food and Strategic Reserves Administration have dispatched 5,000 tents, 10,000 folding beds and 20,000 quilts to the quake-hit areas.

The first team of nine medical experts has set off for the quake-hit region while the second team stands by, according to the National Health Commission (NHC).

Team members are experts in critical care, orthopedics, psychology, epidemic control and sanitation from leading hospitals in Beijing and the Chinese Center for Disease Control and Prevention.

Three national medical emergency teams have been on call while three local medical teams of about 50 members have reached the quake-hit region.

Relief materials from the Red Cross Society of China are on the way, including tents, quilts and coats, as well as several search and rescue teams.

China's armed police forces were also dispatched for rescue soon after the earthquake.

Nearly 800 armed police forces from Sichuan set off for the epicenter for rescue efforts with professional equipment including life detectors and forcible entry tools. More than 1,000 armed police forces from Sichuan Province were assigned as mobile forces for reinforcement.

As of 8 a.m. Tuesday, a total of eight buried people were retrieved from the debris, and over 600 people were relocated by the armed police forces. They have also finished transporting 12 tonnes of supplies and put up over 120 tents.

The quake caused a major highway connecting Yibin and Xuyong County of Sichuan's Luzhou City to be closed. Some sections of other roads were also blocked or closed.

In the provincial capital Chengdu, an early warning system alarmed the public through multiple broadcasting systems about one minute before the earthquake struck. The same system alerted residents in Yibin 10 seconds before the quake hit.

The early warning system uses the theory that radio waves travel faster than seismic waves.

Earthquake research has found that being aware of an earthquake three seconds beforehand can save 14 percent of casualties, 10 seconds can save 39 percent of casualties and 20 seconds can save 63 percent of casualties.