Bulgaria's prime minister has declared a day of mourning after a massive motorway pile-up killed 12 people and injured 50.
The crashes happened during thick fog, which authorities believe was likely the cause.
The incident happened on the main road linking the capital Sofia with another major city, Burgas.
Twelve people have died in a motorway pile-up in eastern Bulgaria involving dozens of vehicles in thick fog, officials said.
Police, firefighters and ambulance crews rushed to the scene near the city of Yambol on the A1 road that links the capital Sofia with the eastern city of Burgas.
Images on local media showed cars and trucks piled up across six lanes of highway, many crushed, overturned, or veered off to the side.
Briefing reporters at the site of the accident, General Secretary of the Interior Ministry, Lyubomir Nikolov, said that fog was the likely cause of the accident which started with a collision between a bus and a truck about 75 kilometres west of Burgas.
Eleven people died at the scene and another died in hospital, Healthcare Minister Katya Ivkova told reporters.
Another 50 people who were injured were taken to hospital, according to the interior ministry.
Yambol Regional Governor Georgi Chalakov told Bulgarian state news agency BTA that about 50 vehicles were involved.
