Two cargo ships have collided in the Baltic Sea between the Danish island of Bornholm and the southern Swedish city of Ystad, Swedish media reported on Monday, citing the Swedish Maritime Administration.
One ship was registered in Denmark, and the other was British, Sweden's public broadcaster SVT said on its website.
"One of them is upside down. We don't know exactly how it happened," SVT quoted Swedish Maritime Administration spokesperson Jonas Franzen as saying.
"The Danish ship had at least two persons on board," Franzen said.
A big rescue operation was underway, SVT said.
Swedish news agency TT cited a Swedish coastguard spokesman saying one of the vessels was 90 metres long, and the other was 55 metres.