Iran's largest warship has caught fire and sunk in the Gulf of Oman, according to reports from semi-official news agencies in the country.
The blaze on board the navy ship began around 2.25am and firefighters were unable to save the vessel.
The Fars and Tasnim news agencies said the support warship Kharg, named after the island that serves as the main oil terminal for Iran, sank near the Iranian port of Jask - some 790 miles southeast of Tehran on the Gulf of Oman.
Photos have circulated on Iranian social media sites showing sailors wearing life jackets as they evacuated the burning vessel behind them.
According to media reports, no one sustained serious injury during the incident and the entire crew of the vessel, 400 at the time of the accident, was evacuated safely.
Iranian state TV said the vessel was a "training ship".
Fars published video of thick, black smoke rising from the ship early on Wednesday morning.
Satellites from the US National Oceanic and Atmospheric Administration (that track fires from space) detected a blaze at the site near Jask.
The Kharg serves as one of a few vessels in the Iranian navy, capable of providing replenishment at sea for its other ships.
It also can lift heavy cargo and serve as a launch point for helicopters.
The warship, built in Britain and launched in 1977, entered the Iranian navy in 1984 after lengthy negotiations that followed Iran’s 1979 Islamic Revolution.
Iran’s navy typically handles patrols in the Gulf of Oman and the wider seas, while the country’s paramilitary Revolutionary Guard operates in the shallower waters of the Strait of Hormuz and the Persian Gulf.
In recent months, however, the navy launched a slightly larger commercial tanker called the Makran it converted into serving a similar function as the Kharg.
Though officials have not offered a cause for the fire, it comes after a series of mysterious explosions that began in 2019 targeting ships in the Gulf of Oman.
The US Navy later accused Iran of targeting the ships with limpet mines, timed explosives typically attached by divers to a vessel’s hull.
Iran denied targeting the vessels, though US Navy footage showed members of Iran’s Revolutionary Guard removing one unexploded limpet mine from a vessel.
The incidents came amid heightened tensions between the US and Iran after then-president Donald Trump unilaterally withdrew America from Tehran’s nuclear deal with world powers.
The sinking of the Kharg marks the latest naval disaster for Iran.
In 2020 during an Iranian military training exercise, a missile mistakenly struck a naval vessel near the port of Jask, killing 19 sailors and wounding 15.
Also in 2018, an Iranian navy destroyer sank in the Caspian Sea.