A fire in a commercial building south of Benin’s capital has killed at least 35 people, authorities said, as they started an investigation.

The gutted and burned ruins of a building in Seme-Podji, 10 kilometers (6 miles) south of the capital Porto-Novo, and the charred remains of cars and motorcycles was all that could be seen in the aftermath of the fire in footage by Benin’s public broadcaster.

A fire official told broadcaster ORTB that the accident happened at a site known for the storage and handling of gasoline. Passersby rescued three people before firefighters arrived, the official, Dallys Ahouangbegnon, added.

The fire broke out on Saturday morning and was “probably started during the unloading of bags of gasoline,” Beninese prosecutor Adam-Bongle Abdoubaki said in a statement published on local outlet benin-news.com.

The dead included one child while more than a dozen people were injured, he said.

Abdoubaki added that a crisis unit was set up to keep the victims’ families informed, collect information to establish the cause of the fire, and determine criminal liability.

“I am dismayed,” local prefecture representative Marie Akpotrossou told the public broadcaster. She blamed the deaths of so many people on the sale of contraband gasoline and said it was high time to take another look at the illegal trade.