ATHENS, Greece (AP) — Authorities in Greece say four crew members have been injured in an engine-room explosion on a ferry at Iraklio port on the island of Crete.

There were no passengers on board when the blast happened on the 33-year-old Blue Horizon ferry, which is used to service the route between Crete’s main port and Piraeus, near Athens.

The Merchant Marine Ministry said the four injured crew members hurt Monday had all been hospitalized. State-run television said one of them was in serious condition.