Racing against time, inclement weather and frequent aftershocks, rescuers dug through rubble of toppled schools, factories and houses looking for thousands trapped underneath as the toll from the deadliest quake to hit China in three decades crossed 12,000 today. The toll now exceeds 12,000 in Sichuan province alone, according to state media, and may go up further as at least 10,000 people remained buried in Mianzhu city in the province while 3,629 people had been confirmed dead and 18,645 were buried under the debris in Mianyang city. Thousands of Chinese troops and medical teams have been dispatched to the worst affected Sichuan province.