Iranian authorities have said there was a “failure to observe safety principles” at the port of Bandar Abbas, where an explosion Saturday killed dozens of people, but testing is required to determine the causes of the blast.

A massive explosion and fire that rocked a port Saturday in southern Iran, purportedly linked to a shipment of a chemical ingredient used to make missile propellant, has killed at least 40 people and injured around 1,000 others, officials said.