A massive explosion and fire on Saturday rocked the Port of Shahid Rajaei in southern Iran, killing at least 40 people and injuring more than 1,000 others. Helicopters and aircraft dumped water from the air on the raging fire through the night into Sunday morning.  

The state-run Islamic Republic News Agency quoted an official as saying the explosion was likely set off by containers of chemicals, but did not identify the chemicals. The agency said late Saturday that the Customs Administration of Iran blamed a “stockpile of hazardous goods and chemical materials stored in the port area” for the blast.

There are reports that the explosion is linked to a shipment of a chemical ingredient used to make missile propellant.

In a first reaction on Sunday, the spokesman of Iran’s defense ministry, Gen. Reza Talaeinik, denied reports that missile fuel had been imported through the port.

“No sort of imported and exporting consignment for fuel or military application was (or) is in the site of the port,” he told state TV by phone. He called foreign reports on the missile fuel baseless.

No one in Iran outright suggested that the explosion came from an attack. However, even Iranian Foreign Minister Abbas Araghchi acknowledged that “our security services are on high alert given past instances of attempted sabotage and assassination operations designed to provoke a legitimate response.”

The Port of Shahid Rajaee is Iran’s largest commercial port and maritime hub, handling approximately 80 million tons of goods annually.