The bodies of 15 people killed when a trailer carrying migrants overturned in Mexico were returned to Guatemala on Thursday and reunited with families who will lay them to rest as the year ends.

In all, 56 people were killed when a truck packed with migrants flipped over in the state of Chiapas earlier this month. Of the 37 Guatemalan nationals identified among the victims, the remains of only 19 have so far been returned.

Guatemala’s foreign ministry has said there are 18 other victims who are still being identified, but whose bodies will be repatriated in the coming days.

The incident underscored the dangers migrants face on the road to the U.S. border, often at the hands of human-traffickers known as coyotes. Dozens of migrants have died from violence or accidents in Mexico over the past decade.

The 15 victims, all male, whose bodies were returned on Thursday were transferred by the Mexican Air Force, Mexico’s government said. The Guatemalan Air Force then transported their bodies in caskets to the homes of their families.

A Mexican government statement said officials have so far identified 50 of the victims from the trailer accident from Guatemala, the Dominican Republic, El Salvador and Ecuador.

Another 74 Guatemalans have been discharged from various hospitals in the city of Tuxtla Gutierrez in Chiapas, near the site of the accident. There are still 27 people hospitalized, more than half of them in serious condition.

Following the incident, the United States, Mexico, Guatemala and other countries pledged to crack down on international people-smuggling networks they blamed for the deaths.