Passengers travelling with Wighlight have been told that their fleet of ferries are safe after the upper deck of a vessel collapsed.
Three passengers and a crew member were treated in hospital for their injuries following the collapse of the deck.
Paramedics along with police, fire crews and the coastguard were called to the Fishbourne terminal on the Isle of Wight shortly before 10.30pm yesterday.
As passengers disembarked the forward mezzanine deck on the starboard side of the ferry, which had nine cars on it, collapsed on to the deck beneath it as it was being lowered.
Vehicles on the lower deck had already left the ferry.
The incident occurred on the Wightlink Ferries St Helen car ferry, which sailed at 9.30pm from Portsmouth to the Isle of Wight with 181 passengers and 11 crew on board.
Karen Woods, a spokeswoman for the company, said the deck ''dropped a few feet and made contact with the lower deck''.
She said: ''One member of the crew and three passengers have been taken to St Mary's Hospital by ambulance. The Isle of Wight ambulance service has confirmed none of the injuries are life-threatening. A member of Wightlink's staff attended the hospital to aid and support customers.''
It is not known whether those injured were in cars on the mezzanine deck or were on the level beneath it.
A full investigation is under way and the incident has been reported to the Marine Accident Investigation Branch.
A spokesman for the Isle of Wight Ambulance Service said the patients were being treated for ''a variety of injuries'', and all were ''conscious and breathing'' when they were taken from the scene.
He said: ''We are not aware of the nature of the injuries. It is very fortunate that it was only four people injured, all things considered.''
A spokesman for Isle of Wight NHS Trust, said the four patients who were taken to hospital as a precautionary measure had now been discharged.
He added: "The Ambulance Service and Trust would like to thank the other emergency services and Wightlink for their support in dealing with this incident.”
Wightlink Ferries said the St Helen car ferry is inspected regularly by external surveyors and last underwent an engineering survey, including its mezzanine decks, in May following its annual refit.
John Burrows, chief operating officer at Wightlink, assured passengers travelling with the ferry compnay that he was satsfied the fleet was safe.
"This is an extremely rare occurance. It will not be happening again in the forseeable future."
He added that the St Helen was brought back to Portsmouth and immediately taken out of service. Some delays were reported on the affected crossing but all outher routes with Wighlight were running to timetable.