The death toll from a sewage tank collapse in east China's Zhejiang Province has risen to 9.

As of 9:06 a.m. on Wednesday, 9 people have been killed and another 4 people who were seriously injured have been hospitalized. All the missing were found and the scene was still being cleaned up, said local authorities.

The collapse occurred around 5:00 p.m. on Tuesday in an industrial park in the city of Haining.

The fire department earlier said they responded to an incident of people trapped in a factory. Stacks fell after a suspected explosion of a 15-meter-high sewage tank located just outside the building. The cause of the blast was not immediately clear and further investigation has been ordered.