Parts of the tourist submersible that imploded on a deep dive to the Titanic, killing five people, have been seen for the first time since the incident. Metal wreckage from the Titan sub was unloaded from the Horizon Arctic ship in St John's, Canada, on Wednesday. Photographs showed metal pieces from the sub covered in tarps before cranes lifted them on to trucks. US Coast Guard officials have said the submersible's landing frame and a rear cover were found among the debris. All five people on board the vessel died on June 18 after it imploded about 90 minutes into a dive to view the famous 1912 shipwreck, which sits at a depth of 3,800 meters (12,500 feet) in the north Atlantic. The submersible's construction included two titanium end caps and a carbon fiber cylinder between them. The debris brought ashore on Wednesday appeared to include both end caps, including the sub's porthole with its window missing, as well as landing frame and the end equipment bay, BBC News science correspondent Jonathan Amos said. So far, five major pieces have been found below the surface in a large debris field near the bow of the Titanic, according to the last update from the US Coast Guard. The agency has launched an investigation into the causes of the Titan disaster, which is in its initial phase. Officials have said they will try to establish what caused the implosion, and make recommendations to prevent future tragedies. The head of OceanGate, which organized the dive, 61-year-old Stockton Rush; British explorer Hamish Harding, 58; Shahzada Dawood, 48, and his son, Suleman Dawood, 19; and French diver Paul-Henry Nargeolet, 77, all died in the incident. OceanGate has since been criticized for its safety practices. Former employees had raised several concerns about the Titan sub, which was not subject to regulation. In email messages seen by the BBC, Rush had previously dismissed safety worries from one expert, saying he was "tired of industry players who try to use a safety argument to stop innovation". In a statement last week, OceanGate said it was "an extremely sad time for our employees who are exhausted and grieving deeply over this loss". — BBC