Refugees prepare to board a train heading to Serbia from the Macedonian-Greek border near Gevgelija, Oct. 25, 2015. Robert Atanasovski/AFP/Getty Images

Bulgaria's interior ministry found 130 refugees believed to be from Syria in a refrigerator truck Saturday crossing over from the Turkish border, Agence France-Presse reported. The government, which has been making 100 arrests a day of refugees hiding while they wait to achieve asylum status, said the health of those discovered was not at risk.

Hiding behind bottles of water were 38 men, 33 women and 58 children, AFP reported. In August, a similar situation resulted in 71 refugees' freezing to death in a refrigerated truck in Austria. About 2,800 refugees have been reported dead or missing across Europe in 2015.

In an effort to avoid becoming a hot spot like Greece, police searched 6,000 vehicles and arrested 495 migrants nationwide Saturday, AFP reported.

Syrians are the largest population of refugees seeking shelter in Europe, the United Nations Refugee Agency said in a report this summer, a position held by Afghans for three decades. Of the 366,402 refugees who arrived by crossing the Mediterranean Sea so far this year, 51 percent -- 186,865 -- were Syrian. Far behind at 12 percent were Afghans, and ranking third were Eritreans at 8 percent, followed by groups from Nigeria, Iraq, Sudan and Somalia.

Of the European host countries, Greece takes on most of the arrivals, with 244,855 so far this year, followed by Italy, receiving 115,000. Seventy-five percent of the refugees are men, 12 percent women and 13 percent children.