A “possible explosion” struck a key shipping lane off Yemen, two maritime agencies said, the latest incident in the vital waterway threatened by Houthi rebel attacks, AFP reports.

The British military’s United Kingdom Maritime Trade Operations issued a warning of a potential explosion striking near a vessel passing through the Bab al-Mandeb strait that separates the Arabian Peninsula from the Horn of Africa.

“The captain reported… the ‘explosion’ occurring two nautical miles off one of the vessel’s quarters while it was transiting,” said maritime security firm Ambrey.