ATHENS, Greece (AP) — A fire broke out on a ferry sailing to the island of Crete from mainland Greece early Wednesday, forcing hundreds of passengers to don life vests and wait on the deck for hours before they were safely evacuated when the ship returned to port.

The fire on the Eleftherios Venizelos ferry started in the parking bay and was contained after activating an automatic extinguishing mechanism. Still, it left smoke billowing out of the ship as it turned back to the port of Piraeus, near Athens. The 875 passengers onboard disembarked using mobile safety stairs from a side entrance of the ship.

"It is a difficult situation, because we are dealing with a large vessel," Fire Service official Yiannis Stamoulis said.

He described the firefighting effort as ongoing.

Hours after the Eleftherios Venizelos docked, smoke continued to rise from the vessel which was surrounded by fire fighters.

Defense Ministry officials said preparations had initially been made to rescue passengers by helicopter before the ferry reached Piraeus, but that option was not considered necessary.

The Merchant Marine Ministry and Greek ferry operator ANEK said all 141 crew members on board were also unharmed.

The fire broke out as the ferry passed the tiny island of Agios Giorgos, 70 kilometers (45 miles) southeast of Piraeus, and was ordered to return. In a statement, the ferry operator said the fire had started at a parking bay used by trucks.

More than 35 million passengers used ferry services in Greece last year, mostly from mainland ports to islands — an increase of 7.4 percent from 2016 as tourism continues to grow.

___

This version corrects the destination of the ferry to Crete.