Video by ITV News Reporter Ria Chatterjee
A large cruise ship has collided with a dock and a tourist river boat on a busy canal in Venice.
Four older female tourists were injured as they tried to run away as the cruise ship rammed the tourist boat.
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.
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.
In a statement, MSC Cruises said that the ship "experienced a technical issue "while maneuvering towards Venice’s VTP cruise terminals for mooring".
It continued: "Albeit the ship was accompanied by two tugs, she grazed the dock at San Basilio.
"This also caused a collision with a river boat that was moored there.
"The investigations to understand the exact causes of the events are currently in progress.
"Regarding these, the company is working closely with the local maritime and other authorities.
"The ship has in the meantime received authorisation to move to be moored at the Marittima terminal, as planned.
"She is now moored there and has begun passenger operations."
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.
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.
Italy's minister for infrastructure and transport, Danilo Toninelli, said they are close to a "solution" to protect the dock and tourism.
He tweeted: "Today's incident at the Port #Venezia shows that they #grandinavi [big ships] no longer have to pass by the Giudecca.
"After many years of inertia, we are finally close to a definitive solution to protect both the lagoon and tourism."
Luigi Bragnaro, mayor of Venice, has said they are waiting for more information and have cancelled a regatta and procession.
"Right now we have to give priority to rescue," he tweeted.
Duncan Ogle-Skan, on holiday in the Italian city, told ITV News he could hear shouts over the ship's horn as it neared the quay.
Venice is a tremendously popular site for both tourists and cruise ships, especially during the summer tourist season.
The MSC Opera was built in 2004. It can carry over 2,675 passengers in 1,071 cabins. According to its sailing schedule, the cruise ship left Venice on May 26 and traveled to Kotor, Montenegro, and Mykonos, Santorini and Corfu in Greece before returning Sunday to Venice.