Three people have been arrested over the deaths of 71 migrants found in a refrigerated lorry abandoned in Austria.
The migrants are likely to have suffocated, according to Hans Peter Doskozil, chief of police in eastern Burgenland province. The 71 included eight women and four children.
A Syrian travel document was found among the bodies indicating that at least some of the dead were refugees fleeing violence in Syria.
It is the latest tragedy in a year that has seen tens of thousands seeking refuge in wealthy European countries.
The refrigerated lorry was found parked in the safety lane of the highway from Budapest, Hungary, to Vienna on Thursday. The bodies were partially decomposed. Post-mortems are being carried out.
At least two of those arrested are Bulgarian citizens and the third has Hungarian identity papers, according to police.
It was the latest tragedy in a year that has seen tens of thousands of people risking all to seek a better life or refuge in wealthy European countries.
German chancellor Angela Merkel said at the Vienna conference she was “shaken by the awful news,” and summit participants held a minute of silence.
“This reminds us that we in Europe need to tackle the problem quickly and find solutions in the spirit of solidarity,” Ms Merkel said.
Migrants fearful of death at sea in overcrowded and flimsy boats as they flee turmoil and war in the Middle East have increasingly turned to using a land route to Europe through the Western Balkans.
But the discovery of the bodies in the truck on the main motorway connecting Vienna to the Hungarian capital of Budapest showed there is no truly safe path.
Thousands cross from Greece daily with the help of smugglers, aiming to reach European Union countries like Germany, Austria or Sweden and apply for asylum. The human traffickers may charge thousands of dollars per person, only to stuff them into trucks and vans so tightly that they often cannot move – or breathe.
Post-mortem examinations would be conducted in the capital later, he said.