A large cruise ship has collided with a dock and a tourist river boat on a busy canal in Venice.
Italian media report that at least five people have been injured in the crash.
The collision happened about 8:30am on Sunday on the Giudecca Canal, a major thoroughfare that leads to Saint Mark's Square in the north-eastern Italian city.
Video of the crash shows the cruise ship, apparently unable to halt its momentum, ploughing into the much smaller river boat and the dock as dozens of people run away in panic.
Venice is a tremendously popular site for both tourists and cruise ships, especially during the summer tourist season.
The cruise ship's owner, MSC Cruises, said the ship, the MSC Opera, was about to dock at a passenger terminal in Venice when it had a mechanical problem.
Two towboats guiding the cruise ship into Venice tried to stop the massive cruise ship, but they were unable to prevent it from ramming into the river boat.
"The two towboats tried to stop the giant and then a tow cable broke, cut by the collision with the river boat," Davide Calderan, president of a towboat association in Venice, told the Italian news agency Ansa.
Mr Calderan said the cruise ship's engine was locked when the captain called for help.
Following the accident, calls for banning cruise ships in Venice, long a source of contention in the over-extended tourist city, were renewed.