The death toll from a collision in Sydney's famous harbor between a runabout laden with young joyriders and a fishing boat has risen to six, AP quoted officials as saying Friday. The U.S. Consulate named one of the victims as 25-year-old Jessica Savanna Holloway. It did not provide further details, though local media reported that Holloway is from Texas and was working as a youth worker in Australia. Four others were killed in the collision shortly before 3 a.m. Thursday, and another died later in a hospital. Eight others were injured. Apart from Holloway, all were Australians. Dr. Ray Raper, head of intensive care at the Royal North Shore Hospital where the injured were treated, told reporters Friday the sixth victim died from severe head injuries he suffered in the collision. All of the dead and injured were aboard the seven-meter (23-foot) half-cabin cruiser, which was licensed to carry eight people but had 14 aboard when the crash occurred. They were aged in their late teens and early 30s. Witness and police descriptions indicated the group took the boat out for a late-night tour of the harbor after drinking at a hotel in the harborside suburb of Balmain. Police declined to speculate about the cause of the collision, but said alcohol, speed, and lighting would be investigated, as well as whether the victims were wearing lifejackets. The crash occurred near Bradley's Head in a favored sightseeing area of the harbor, home to Sydney Opera House and Sydney Harbor Bridge landmarks. Once a bustling commercial port, the harbor is now dominated by pleasure craft, passenger ferries and cruise ships. A small commercial fishing fleet operates from the harbor, and the 12.5-meter (41-foot) trawler that struck the cruiser was heading out to sea. The cruiser was owned by a boat repair company whose officials said Friday permission for its use had not been given Thursday night. Sydney Ship Repair and Engineering said in a statement a former contractor for the company was among the injured, and may have taken the boat for a joyride. Damage to the rear of the cruiser prompted early speculation Thursday that it was hit from behind. But Senior Inspector Glenn Finniss said later Thursday the cruiser appeared to have been hit near the center of one side, and was damaged along that side and at the back. Police and witness descriptions of the two boats' activities before the crash suggest the two vessels were heading toward each other, with the fishing vessel heading away from downtown and the cruiser heading toward it. The most recent fatal crash in Sydney Harbor was in March last year, when a passenger ferry plowed into a pleasure boat under the harbor bridge, killing four people. The most notorious was in 1927, when a mail steamer collided with a ferry, sinking the ferry and killing 40 people.