Four workers were killed when they breathed in toxic sulphur fumes from the tank of a truck near the southern Italian city of Bari, according to Reuters.

Local police said a worker was overcome by the fumes while cleaning the inside of the tank. Three other workers died when they entered the tank to help him, and a fifth worker is in a critical condition.

The high number of workplace deaths is considered by many to be a national scandal in Italy, where recent draft government legislation aimed at tightening safety conditions has not been approved by parliament, according to Reuters.