More than 340 children have died while trying to cross the Mediterranean Sea in the past five and a half months, three agencies announced Friday, saying the death toll continues to climb.

The actual number of drownings could be higher, the International Organization for Migration (IOM), United Nations Children’s Emergency Fund (UNICEF) and the U.N. Refugee Agency said in a joint statement, because authorities may not have been able to recover every child’s body.

Still, the agencies said the current number of deaths equates to an average of two children per day since September 2015, as more migrant families try to reach Europe in search of better lives.

The U.N. Refugee Agency has said that more than 1 million migrants and refugees traveled to Europe by sea alone last year, most of them fleeing war-torn countries. More than 3,700 died.

In Friday’s announcement, the three agencies said migrants often travel in overloaded, poor-quality boats that place them at a higher risk of capsizing, particularly in rough seas.

“Clearly, more efforts are needed to combat smuggling and trafficking,” U.N. High Commissioner for Refugees Filippo Grandi said in a statement.

The IOM says 90,756 adults and children have traveled across water to Italy and Greece during the first 49 days of 2016, and 411 of them have died. Some 7,461 have died since January 2014.

The agencies called for actions to ensure migrants travel safely, noting that many of them are currently trying to join relatives in Europe. They said some 36 percent of migrants are children.

“This is not only a Mediterranean problem, or even a European one,” IOM Director General William Lacy Swing said in a statement. “It is a humanitarian catastrophe in the making that demands the entire world’s engagement.”