A fire broke out in one of two engine rooms onboard Royal Caribbean’s Splendour of the Seas during an October sailing.

Twenty-one people were treated for smoke inhalation according to the cruise line’s tweets.

The cruise departed Venice and the fire started when the ship was sailing toward Argostoli, a town on the Greek island of Kefalonia.

One guest and 19 crew members were treated for smoke inhalation and released. One crew member was still being treated on Thursday, according to Royal Caribbean.