A cargo ship has sunk after hitting a naval mine in the Strait of Hormuz, Iran’s Revolutionary Guard Corps navy said on Wednesday.

State television quoted a Guard statement saying the vessel was on what it called an illegal and dangerous route when it struck the mine that morning. The statement said the ship was carrying 2,500 containers and caught fire first. Few details were given, including the fate of the crew.

It is the first time Iran has reported a ship sinking after hitting a mine during the war. Iran has repeatedly warned ships against passing through the strait without its approval. The U.S. military has been guiding ships along a route off Oman, on the far side of the strait.

The sinking has not been independently verified. The United Kingdom Maritime Trade Operations monitor had issued no report.

The strait is a key route for global oil and cargo shipping, which matters to Sri Lanka as an importer of fuel.