An apparent submarine attack on an Iranian warship off the coast of Sri Lanka has left at least 101 people missing, one dead and 78 injured, sources in Sri Lanka’s navy and defence ministry told Reuters on Wednesday.

The vessel, IRIS Dena, is a Moudge-class frigate belonging to the Iranian Navy and was reportedly operating in international waters when the incident occurred.

Distress Call At Dawn

The 180-crew frigate had issued a distress call at dawn, prompting a response from Sri Lankan naval authorities. Rescue efforts were underway as officials worked to account for the missing sailors.

Heavily Armed Warship

The IRIS Dena frigate was armed with heavy guns, surface-to-air missiles, anti-ship missiles and torpedoes and was capable of carrying a helicopter, making it a significant asset within Iran’s naval fleet.

Sri Lankan authorities have not officially confirmed the cause of the strike, and investigations into the incident were ongoing.