MILAN (AP) — An explosion at a fuel depot in the central Italian region of Tuscany on Monday killed at least two people and injured 14 others, authorities said.

The blast collapsed a building with offices, where three people were believed missing, regional environmental official Monia Monni told SKY TG24.

The explosion happened at an ENI fuel depot north of Florence, sending a dark plume of smoke into the air. Witnesses kilometers away reported a large bang and tremors.

Italy’s ENI oil company said the cause of the blast at the depot in Calenzano, near Florence, was under investigation.

Flames were quickly contained, preventing the fire from spreading to storage tanks from a loading dock area where the explosion occurred.

Residents were advised to keep their windows closed out, but environmental officials later determined that the air quality was safe. The smoke temporarily interrupted regional train services.