On Sunday the MSC Opera, a cruise ship owned by MSC Cruises, smashed into a dock and a smaller vessel in Venice, Italy. At least four people were injured during the accident, which has caused MSC to cancel several upcoming port calls to the city. A video from the incident was captured by a passenger onboard the Opera and was uploaded to YouTube shortly after.

The cause of the collision appears to be an engine failure suffered by the Opera as it was approaching the dock. The captain of the cruise ship reported to the harbor master that the engine was “locked” but still producing thrust, propelling the vessel toward shore. Several tugboats were tied to the ship and were attempting to push the vessel away from land as the Opera’s captain ordered both of the vessel’s anchors to be dropped; however, both measures were unsuccessful in preventing the crash.

“We have activated all possible procedures to avoid impact,” said MSC Opera’s captain before the collision, according to a report from the BBC.

Officials from MSC announced the cancellation of the Opera’s current voyage in order for a more thorough investigation. The vessel will also undergo repairs to fix the damage to the ship’s hull. The other vessel involved in the incident, the Uniworld-owned River Countess, will also be taken out of service until at least mid-July. According to officials from Uniworld, the majority of the passengers who sailed on the River Countess had already disembarked when it was struck by the Opera. Had more people been aboard during the collision, the human toll could have been much higher.

“At the time of the accident, only 26 of the ship’s 130 passengers remained on board, with most having already disembarked and transferring to flights home,” Uniworld officials wrote in a statement, according to Cruise Critic.

This latest incident has reignited a debate in Italy over whether or not to allow cruise ships to dock at the San Basilio Cruise Terminal in Venice. Many Italian politicians are concerned the large ships pose extreme environmental and pollution risks to the city, and others are concerned the large wake made by the ships is causing much of surrounding coastline to erode.

The fear of cruise ship-generated pollution may not be unfounded. On Monday, Carnival Cruise Lines pled guilty to violating maritime environmental laws. According to Carnival’s CEO Arnold Donald, the cruise line knowingly discharged wastewater in Glacier Bay National Park in Alaska and also dumped trash and food waste near the Bahamas. As a result, Carnival has been ordered to pay a fine of $20 million, according to a report from Florida Today.