TEHRAN -- The death toll from a massive explosion at a port in Iran's southern province of Hormozgan on Saturday has reached 40, and the government has announced one day of national mourning, Iran's IRIB news agency reported on Sunday.

The explosion and the subsequent fire left more than 1,000 people wounded, of whom 197 were hospitalized, the IRIB quoted Hormozgan's Governor Mohammad Ashouri Taziani as saying.

The cause of the incident has not been determined yet.

The Iranian government's spokeswoman, Fatemeh Mohajerani, in a post on social media platform X, said the administration had declared Monday a day of national mourning.

Iranian President Masoud Pezeshkian visited the port on Sunday to assess the circumstances of the blast, and visited some of the injured, according to a statement from his office.

Hossein Sajedinia, head of the National Disaster Management Organization, told the IRIB that firefighting teams from five provinces were working to contain the fire, predicting that the blaze would be curbed in a few hours.

He said some of the containers at the port contained flammable materials, such as pitch, and some others had chemicals in them.

Despite the incident, the port's wharfs have resumed operations and cargo handling, according to the official news agency IRNA.