Six seamen are missing after a ship sank in the Irish Sea overnight but two people have been rescued. The cargo vessel, which has not been named, called the coastguard in Holyhead, north Wales, around 0200 GMT on Sunday. The crew reported the hull was thought to have cracked in bad weather and the ship was taking on water. The coastguard sent out a mayday relay and several vessels responded and went to the scene to assist. The vessel is reported to have sunk 20 miles north-west of the tip of the Llyn peninsula. A helicopter from RAF Valley in north Wales and another from Dublin Coastguard arrived at the scene, as well as lifeguard boats from Pwllheli and Porthdinllaen. Two people were rescued from the water and taken to RAF Valley but the search is ongoing for the remaining six crew members. The coastguard report very difficult conditions in the dark with rough seas and high winds.