Madinat ash ShamalProjectiles hit a tanker 58 miles off Qatar.
UKMTO reported casualties without a toll, and shipping trade press calls it the first tanker attack in the western Gulf in weeks.
Hormuz carried 20% of global crude and gas before the war, and UKMTO counts 9 tanker attacks there this month.
Middle East crude exports still reached 18.3 million barrels a day on 30 September, above pre-war levels, Kpler data show.
Qatar, whose economic zone includes the site, has not commented, and UKMTO says authorities are investigating.
Sources: Al Jazeera Online, Mehr News Agency