Parents hold photos of their dead children today as they walk through the ruins of a school in Wufu, China. Parents of the 200 children killed when the school collapsed in the May 12 earthquake are demanding an investigation into shoddy construction.

PENGZHOU, China — Earthquake survivors living downstream from lakes formed by blocked rivers were being evacuated today for fears that aftershocks could unleash flooding. The death toll rose to more than 55,000, and nearly 25,000 people remain missing.

Hardest-hit Sichuan province also announced plans to rebuild within three years, as it copes with the aftermath of the May 12 temblor that left some 5 million homeless.

Nearly three dozen new lakes were formed after the quake threw down debris that formed barriers across rivers, with water pooling behind them. Those barriers could collapse, unleashing flooding, so they are being monitored by experts, including some dropped in by parachute, said Zhu Bing, deputy director of the Sichuan water resources bureau. Rain was also was forecast in the region next week.

"In the short-term, we don't think there's any danger," he told reporters in Beijing. "But after all, it's in the disaster area, with aftershocks. If there is a strong aftershock or a strong thunderstorm, there is the danger of collapse."

The death toll rose to 55,740 and another 24,960 people remain missing, said the State Council, China's Cabinet.

As many as 9,000 injured will be transported to other provinces, Vice Governor Li said, as the large casualty toll has overwhelmed local hospitals in Sichuan.

He said more psychologists were also needed to help survivors cope with the tragedy, especially children orphaned by the quake along with students who saw many classmates killed in collapsed schools.