A truck found abandoned on an Austrian highway contained the bodies of 71 migrants, including four children, and four suspects in the case have been arrested in Hungary, said Austrian and Hungarian authorities on Friday.
The dead appear likely at this point to have been Syrian refugees and to have died from suffocation, but forensic investigators are still working on establishing identities and confirming the cause of death, said Hans Peter Doskozil, chief of police in the eastern Austrian state of Burgenland. The bodies -- belonging to 59 men, eight women and four children, including a 1- or 2-year-old girl and an 8- or 9-year-old boy -- are partially decomposed.
Hungarian police said in a statement that they had arrested three Bulgarian nationals and one Afghan in connection with the case. Detectives have searched a number of homes and questioned about 20 witnesses.
Doskozil said one of the three Bulgarians arrested is apparently of Lebanese descent and was the owner of the refrigerated truck, which formerly belonged to a Slovakia-based meat-transporting firm. The suspects could be part of a larger Bulgarian-Hungarian human trafficking organization, he said.
The vehicle and its gruesome contents were discovered Thursday on the side of a highway connecting Austria and Hungary. Many of the thousands of migrants who have been landing in southern Europe are desperate to reach richer northern nations such as Germany and Sweden, which have taken in vastly more refugees than their neighbors and offer more generous benefits.
In recent months, migrants hoping to reach Europe have switched from perilous sea crossings from North Africa to mostly overland routes from Greece and through Balkan nations such as Macedonia and Serbia. While many are refugees from the civil war raging in Syria, others are fleeing violence, instability or poverty in places such as Iraq, Afghanistan and Eritrea.
Doskozil said a Syrian travel document found on one of the bodies suggests that the migrants were from that country. They do not appear to be African.
More than 310,000 people have crossed the Mediterranean to Europe so far this year, eclipsing the total for all of 2014, according to the United Nations. About 200,000 migrants have landed in Greece alone.
So far, the crossings of the Mediterranean from North Africa to Italy have been the deadliest, with about 2,400 people killed making the attempt this year.
That toll looked set to rise Friday as rescue operations continued off the coast of Libya, where two boats carrying 500 migrants were reported to have capsized. The Reuters news agency said that as many as 200 passengers were feared drowned.
The number of people perishing on overland crossings has been tiny in comparison. But the truckload of bodies found Thursday opened another chapter of danger and despair in Europe's swelling migrant crisis.
The discovery of the bodies in the truck, near the eastern Austrian town of Parndorf, was made Thursday morning just as the leaders of Germany and several Balkan nations were meeting less than 30 miles away in Vienna to discuss the crisis.
Chancellor Angela Merkel of Germany, whose country is expecting a staggering 800,000 applications for asylum this year, said she was "shaken" by the news and pledged to help the poorer Southern European nations where migrants are first landing on the continent.
But the leaders were unable to settle on a unified approach to dealing with the waves of migrants and refugees arriving on their shores. The disagreement reflected the wider disarray of the 28-nation European Union's response to the crisis.
Doskozil, the police chief, said the truck appears to have begun its journey near Budapest on Wednesday and crossed into Austria sometime that night. By the time authorities examined the vehicle Thursday morning, the people in the back might already have been dead for up to 48 hours.
Hungary has become a magnet for migrants because it belongs to the EU's vast passport-free travel zone that stretches from Greece to France but that excludes most Balkan nations. The government in Budapest is trying to block migrants entering from non-EU neighbor Serbia by building a fence, including razor wire, along the nearly 110-mile-long border between the two countries.
But thousands have slipped through anyway, including 3,200 detained by Hungarian authorities Wednesday -- the most in a single day for the Central European nation during the present crisis.
The Hungarian government is also trying to crack down on human-smuggling rings, which have often shown scant concern for the lives of those who hire them. The Associated Press reported that authorities in Budapest arrested 21 suspected traffickers Wednesday and Thursday and impounded 16 vehicles carrying 112 migrants.
Earlier this month, Austrian authorities discovered more than 80 migrants locked in the back of a truck traveling on another stretch of highway in the eastern part of the country. The group had been inside the truck for 12 hours, and had pierced holes in the vehicle to let in air and relief from the summer heat.
The truck packed with dead bodies was dented on one side. Police are unsure when the damage was caused but acknowledged the possibility that those jammed inside had tried to punch through for ventilation or to escape.
"This tragedy underscores the ruthlessness of smugglers who have expanded their business from the Mediterranean sea to the highways of Europe," said Melissa Fleming, spokeswoman for the U.N. High Commissioner for Refugees in Geneva. "It shows they have no regard for human life and are only after profit."