XINING - China poured workers and equipment into a mountainous Tibetan region Thursday in a bid to find survivors more than a day after strong earthquakes killed more than 600 people and injured thousands.The series of quakes flattened buildings across remote western Yushu county and sent survivors, many bleeding from their wounds, flooding into the streets of Jiegu township. State television showed block after devastated block of toppled mud and wood homes. Local officials said 85 percent of the buildings had been destroyed.Survivors spent the night outdoors, where temperatures fell below freezing and aftershocks continued, residents said. With limited medical supplies and doctors, survivors with broken limbs could do no more than wait for help."This feels like a war zone. It's a complete mess. At night, people were crying and shouting. Women were crying for their families," said Ren Yu, general manager of Yushu Hotel in Jiegu, who said he felt at least five aftershocks overnight. "Some of the people have broken legs or arms but all they can get now is an injection. They were crying in pain."Rescue work focused on several collapsed schools, with the state news agency saying at least 56 students died. Worst hit was the Yushu Vocational School, where the officials Xinhua News Agency cited a local education official as saying 22 students died, 20 of them girls.