Two people are feared to have died after two cargo ships collided in the Baltic Sea off the Swedish coast early on Monday, causing one to overturn.
Rescue boats and helicopters have so far failed to locate the pair who were on board the capsized boat, the Danish-registered Karin Hoej.
The other vessel involved was the UK-flagged Scot Carrier.
A spokesman for the Swedish Maritime Administration (SMA) said screams had been heard from the water. “It is very cold and dark,” Jonas Franzen told the BBC. “The water is about 4C (39F) and the air is about 5C (41F).”
The incident occurred in an area of the Baltic Sea between the southern Swedish coastal town of Ystad and the Danish island of Bornholm, he said.
Mr Franzen said a distress call was received at about 03:30 local time (02:30 GMT) on Monday. When a rescue team later approached the area, they reported “hearing screams in the water”.