State television showed rescue teams looking for survivors in the rubble of the two-story residential building located near a historic marketplace in the old district of the city of Ahvaz, capital of oil-rich Khuzestan province.

“The gas explosion led to the complete destruction of a two-story residential building… and four nearby residential buildings and six shops,” Ebrahim Qanbari, head of the fire department in Ahvaz, was quoted as saying by the semi-official Mehr news agency.

Four men and one woman were killed, and nine people were injured, Qanbari said.

Some of the explosions in the past few months appeared to be linked to Iran’s deteriorating infrastructure, while others may have been security-related such as blasts at sensitive military and nuclear sites.

According to the local reports, the explosion on Tuesday was in the port area of Beirut containing warehouses. The authorities fear many casualties.

A UN tribunal is due to issue its verdict on Friday in the trial of four suspects in the murder by car bomb of Hariri. All the four suspects are members of the Iranian-backed Hezbollah group, which has consistently denied any role in Hariri’s death.

There are unconfirmed reports of a second blast, which is reported to be at the Hariri’s residence.

Lebanon’s health minister has spoken of many injuries and extensive damage, while the cause of the explosions is not yet clear.