Authorities in Greece have reported that four crew members have been injured in an engine-room explosion on a ferry docked at Heraklion port on the island of Crete. There were no passengers on board when the blast occurred on the 33-year-old Blue Horizon ferry. It had completed the Piraeus-Heraklion route early in the morning and was moored in the port. The Hellenic Ministry of Shipping and Island Policy said the four injured crew members were transferred to hospital. ERT has reported that one of the four crew members is in a serious condition. all been hospitalized. Ert state television said one of them was in serious condition.