CHENGDU, China, July 25 , SPA -- Death toll rises to four as one injured died in hospital, after fallen rocks smashed a bridge early Saturday in southwest China's Wenchuan County, the epicenter of last year's devastating earthquake, Xinhua reported today 11 injured were under treatment in hospital, said a police officer of the Wenchuan county public security bureau. Vehicles plunged into the Minjiang River when huge rocks washed off by continuous heavy rains from a nearby mountain hit and broke a bridge pier at about 5 a. m., destroying the Chediguan Bridge which they were riding on, said an official with the information center of Wenchuan County, Aba Tibetan and Qiang Autonomous Prefecture. More than 100 meters of the 300-meter-long bridge collapsed, the official said. At least seven vehicles were found destroyed, including six trucks and one minibus, said the official, adding that all the injured were sent to hospital. Rescuers said they were not sure how many vehicles had plunged into the river, but added casualties might still rise if more vehicles were found in the river. The Chediguan Bridge is called a lifeline for the reconstruction of Wenchuan. The bridge is part of the No. 213 national highway, a major traffic line linking Wenchuan with other areas. The highway, which plays a key role in restoring local tourism and production, was interrupted. More than 10,000 vehicles pass the bridge every day, which reopened to traffic in May. --SPA An 8-magnitude earthquake struck Wenchuan County on May 12, 2008, leaving about 87,000 people dead or missing and injuring more than 370,000 others--SPA www.spa.gov.sa/687359