DUBAI (Reuters) – Authorities in the United Arab Emirates are trying to extinguish a fire on a Panama-flagged oil tanker off the coast of the emirate of Sharjah, the Federal Transport Authority said on Wednesday.

The tanker, which the FTA said was not carrying an oil cargo at the time, was undergoing maintenance when the fire broke out. The crew sent out a distress signal and have been rescued.

“A proper investigation is in progress”, an official at the UAE National Media Council said.

Ships in the area were alerted through an advisory, seen by Reuters, which said an oil tanker was on fire. The United Kingdom Maritime Trade Operations (UKMTO) said it had received reports of a vessel on fire 21 nautical miles northwest of Sharjah.

Separately, a spokesman for the U.S. Navy’s Bahrain-based Fifth Fleet said they were aware of an incident off the coast of Sharjah and were monitoring the situation.

Writing by Lisa Barrington in Dubai; Editing by Matthew Lewis and Tom Brown