The frigate Iris Dena sent out a distress call about 40 nautical miles (75 kilometers) off the coast of Sri Lanka, but the cause of the sinking is still unknown.

Sri Lanka says it has recovered several bodies and rescued 32 injured sailors after an Iranian warship sank just outside its territorial waters.

Authorities told Al Jazeera that the frigate Iris Dena, located about 40 nautical miles (75 kilometers) off the coast of Galle in southern Sri Lanka, sent out the distress call between 6am and 7am (12:30am-1:30am GMT) on Wednesday.

The cause of the disaster is still unknown. There were about 180 crew members on board the ship, and search and rescue operations were underway.

The Iranian frigate had just returned from taking part in the 2026 International Ship Review in the eastern Indian coastal city of Visakhapatnam last month.

Sri Lanka’s Foreign Minister Visita Heras told parliament that the navy had received information that the ship was in distress and the government had sent ships and air force aircraft on a rescue mission.

A Sri Lankan Navy spokesperson said no other ships or aircraft were observed in the area where the Iranian warship sank.

Al Jazeera’s Minere Fernandes, speaking from outside the hospital in Galle where the injured crew members were taken, said Sri Lankan authorities were trying to figure out what happened to about 150 other crew members.

“The government has not said anything about the potential causes of the accident,” she said.

Fernandes said officials from the Iranian embassy in Colombo had sent two officials to Galle “to talk to the survivors to understand what happened on board.”

The warship’s sinking came amid a five-day U.S. and Israeli airstrike on Iran that killed about 800 people, including Supreme Leader Ali Khamenei and dozens of schoolgirls.

The Iranian government responded with drone and missile attacks on U.S.-linked assets in Israel and the Gulf states, resulting in multiple deaths. Six U.S. military personnel were killed and many others were injured.