Rescue workers counted dozens of victims Friday from the increasingly desperate tide of humanity sweeping into Europe fleeing war, oppression and poverty. Austrian police said 71 people likely suffocated in an airless truck and authorities estimated 200 people drowned off the Libyan coast when two overloaded boats bound for Europe capsized.

Authorities around an unsettled world have struggled to respond to the largest global movement of people since World War II. In Europe, thousands of people a day are boarding flimsy boats to Italy or Greece, and thousands more are placing themselves at the mercy of human-trafficking gangs and ordinary thugs as entire families slog for days or weeks through the countryside of the western Balkans toward what they hope will be a brighter future.

The U.N. refugee agency says more than 300,000 migrants and refugees have sought to cross the Mediterranean Sea this year — nearly 40 percent more than in all of 2014, which saw the highest numbers ever recorded. The vast majority are fleeing war, conflict or persecution in countries including Syria, Afghanistan and Eritrea.

The International Office of Migration has recorded 2,432 deaths linked to Mediterranean crossings this year, but countless more have vanished beneath the waves out of sight of rescuers. The official count was set to rise Friday as authorities counted the dead from three shipwrecks off the Libyan coast.

Two ships went down on Thursday alone off the western Libyan city of Zuwara. Hussein Asheini of Libya's Red Crescent, said at least 105 bodies had been recovered, adding: "a coast guard team is still diving in and checking inside to see if there's anyone else."

About 100 survivors were rescued from the two boats, according to the United Nations High Commission for Refugees, and at least 100 more were believed to be missing.

An Associated Press photographer saw workers pulling bodies from the water, and several victims floated face-down in a flooded boat as it was towed into the harbor. At least one of them, a man, was wearing a life vest. The dead were put into orange and black body bags and laid out on the waterfront.

Lawless Libya is a prime setting-off point for migrants, as unscrupulous human traffickers fill boats they know could never reach European shores in the hopes that rescuers will pick up their cargo and take them to Italy.

Often, the smugglers force migrants below deck where their chances of survival are even dimmer. Rescuers who boarded one boat Wednesday counted 52 people who suffocated to death in the hold, according to the U.N. refugee agency. Survivors said the smugglers beat them with sticks to keep them below deck, and one said they demanded money to let the migrants come up to breathe fresh air.

It's a shorter sail from the coast of Turkey to the Greek islands, and thousands more — most of them refugees from Syria and Afghanistan — are making that trip every day in small inflatable boats that aren't designed for open seas. Greece's coast guard said Friday that it had rescued 665 people from 20 boats in the previous 24 hours. Hundreds more presumably made the trip on their own, and the U.N. says 200,000 have made the trip so far this year.

Once they arrive in Greece or Italy, migrants still face long and dangerous journeys to their final destinations. From Greece, the primary route involves trips by foot and train through Macedonia, Serbia and Hungary before heading into western Europe.

Hungarian police arrested four people overnight after 71 migrants — including included eight women and four children — were found dead in the back of a refrigerated truck abandoned on Austria's main highway.

The suspects, allegedly part of a larger Bulgarian-Hungarian smuggling ring, include an Afghan and three Bulgarians, one of whom owns the truck, Hungarian national police spokeswoman Viktoria Csiszer-Kovacs said. Police raided houses and questioned almost 20 others in the case.

Hans Peter Doskozil, chief of police in eastern Burgenland province, said the migrants likely suffocated. At least some of the dead were Syrian, travel documents indicated, though most of the partially decomposed bodies remained unidentified.

The victims included eight women and four children, the youngest a girl who looked to be 1 or 2.

The U.N. High Commissioner for Refugees appealed to authorities to crack down on smugglers and to expand safer, legal ways for refugees to reach Europe.

Melissa Fleming, the agency's spokeswoman in Geneva, said the deaths of the 71 migrants found in Austria illustrate "the desperation of people seeking protection or a new life in Europe."

"We believe this underscores the ruthlessness of people-smugglers who have expanded their business from the Mediterranean Sea to the highways of Europe," she said. "It shows they have absolutely no regard for human life."

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Associated Press writers contributing to this report included Barry Hatton in Lisbon, Portugal; Alison Mutler in Bucharest, Romania; Pablo Gorondi in Budapest, Hungary; and Jamey Keaten in Geneva.