At least six people reportedly drowned when a tourist submarine sank off the coast of Egypt on Thursday. Another nine were injured, four of whom are in critical condition, according to local media reports.

The submarine, called Sindbad, was conducting a sea tour off the coast of Hurghada, a beach town resort stretching some 40km along Egypt’s Red Sea coast, and was carrying 44 passengers. Rescue teams have managed to save 29 people, according to the Egyptian newspaper Al-Masry Al-Youm.

The Red Sea Security Directorate received an alert about the incident in front of the marina of a “well-known hotel” that has not yet been named by local sources. A total of 21 ambulances were dispatched to the accident scene, transporting the injured to local hospitals.

The 44 passengers on board were of various nationalities and were on a marine excursion to observe Egypt’s coral reefs and tropical fish. The submarine had been operating tourist trips in Hurghada for several years.

According to the company Sharm Hurghada Excursions, the submarine tour in Egypt lasts three hours and costs 81 euros for adults and 42 euros for children.

So far, the cause and exact circumstances of the sinking have not been officially confirmed or announced.