Greek authorities say a passenger ferry has struck the dock while tying up in the northwestern port of Igoumenitsa, leaving 11 people injured, including six children and two adults accompanying them on a school trip.

The Merchant Marine Ministry said the ferry had just arrived from the island of Corfu Wednesday morning with 187 passengers and 15 vehicles on board when it struck the dock for as yet unknown reasons. The injured were transported to a health center in Igoumenitsa for first aid treatment.

Three of those, who were not part of the school trip, were to be transported to a hospital for further checks but none of the injuries was believed to be serious, the ministry said. It was not immediately clear how the passengers were injured.