Divers in northern Italy have recovered the last two bodies of workers killed by an explosion that collapsed and flooded several levels of an underground hydroelectric plant, bringing the total number of confirmed dead in the incident to seven.

The explosion at the Enel Green Power plant, in northern Bologna province, occurred on Tuesday at a depth of some 40 metres (130 feet) below water level.

Four other workers who were wounded in the massive blast are currently in hospital with two of them still in a serious condition, officials said.

Divers who worked for more than two days to recover the victims’ bodies likened the scene to an underwater earthquake-struck building.

The blast at the Bargi plant happened during work to increase the plant’s efficiency, the company said in a statement.

A fire broke out when a turbine exploded on the eighth floor below the surface, flooding the floor below.

The cause is still unknown.

Local prosecutors have opened a probe into the accident.