Eight US Marines were injured two weeks ago when an Iranian anti-ship cruise missile struck a vessel they were operating on in the Strait of Hormuz, NBC News reports, citing three US officials, according to Anadolu Agency.

The report says the Marines were not seriously injured but suffered smoke inhalation and possible traumatic brain injuries after experiencing concussion-like symptoms, including headaches.

Seven of the Marines were enlisted personnel, while the eighth was an officer. All eight returned to duty shortly after the Sept. 14 attack, according to the officials.

The Marines were operating as part of a battalion landing team when the Iranian missile struck the vessel, they say.

The officials say the vessel was not a US Navy ship but declined to specify its type, referring to it only as a maritime vessel.