HANGZHOU -- An estimated nine people were buried in the debris after four residential buildings collapsed Thursday morning in Wenzhou, an industrial city in eastern China's Zhejiang province, local authorities said.

The victims were from two families, according to sources with the local government in Wencheng county, where the accident occurred around 8 am.

The buildings were four to five stories tall and located in Dahui village, Baizhangji township.

After the accident, the city and county governments immediately deployed a joint emergency response team of police officers, firemen and medical workers, but they had made little progress as of 1 pm.

"The scene is quite chaotic, as if the place had been leveled by an earthquake," a rescuer told Xinhua by telephone. "We have to work very carefully because the wreckages of the ruined buildings are joined to homes still standing."

One of the adjacent homes, he said, was already damaged with a big hole in its outer wall.

Investigators are yet to confirm the cause of the accident, and it has been largely cloudy in Wencheng over the past few days, with no rain, high winds or any extreme weather or geological conditions.