At least 18 people were found dead in Bulgaria in an abandoned lorry near the capital Sofia, the country's interior ministry said on Friday.
“According to initial information, the truck was transporting illegal migrants — a total of about 40 people, who were hiding … under transported timber,” the ministry said.
The survivors were taken to hospital for medical treatment, it added.
Eight of the people taken to hospital were in serious condition, Bulgaria's health emergency centre told state news agency BTA.
Police were seeking to identify the lorry's drivers, who had fled, the statement said.
EU-member Bulgaria, which serves as a gateway into the bloc, has been trying to tighten security to stop a rising number of people seeking to cross the border.
In a bid to stem the flow, Bulgaria has stepped up controls along the 234-kilometre (145-mile) barbed wire fence covering almost the entire border with Turkey.
Austria and the Netherlands have blocked Sofia's bid to join the Schengen border free zone.
