The blast occurred as Iran began a third round of nuclear talks with the United States in Oman. The cause wasn't immediately clear.

A massive explosion and fire rocked a port Saturday in southern Iran purportedly linked to a shipment of a chemical ingredient used to make missile propellant, killing four people and injuring more than 500 others.

Footage filmed by a driver, and verified by the BBC, shows the moment a massive blast shook the Shahid Rajaee port on Saturday morning, near the southern Iranian city of Bandar Abbas. At least four people have been killed and 500 more injured in the explosion,