A cruise ship lost control in a Venice dock on Sunday, ramming into a tourist boat and injuring four people.
People ran away from the dock as the 13-deck ship ploughed into the much smaller river boat.
The injured were said to be four women from Australia, New Zealand and the US, who were slightly hurt as they escaped.
"When we saw the ship bearing down on us, everyone began shouting and running," a sailor on the smaller boat told Italian media.
"I didn't know what to do. I got away quickly, jumping to get on shore."
The MSC Opera experienced a mechanical problem that caused the engine to fail as it was docking on the Giudecca Canal, which leads to St Mark's Square, owner MSC Cruises said.
Venice is an extremely popular tourist destination, with 20 million visitors flocking to the canal city every year.
The incident has reignited calls for large cruise ships to be banned from the city’s waterways.
"Today's accident in the port of Venice proves that cruise ships shouldn't be allowed to pass down the Giudecca any more," said Danilo Toninelli, the Italian Transport Minister.
Environmental campaigners say the waves created by the ships chip away at the foundations of the city, which suffers regular flooding, while the high number of tourists the boats bring cause further environmental damage.
The MSC Opera was built in 2004 and can carry more than 2,675 passengers in 1,071 cabins.
The ship had a power failure in 2011 in the Baltic, forcing about 2,000 passengers to be taken off in Stockholm.