(CNN)As Venezuelans flee their country in search of safety and economic security, another set of dangers awaits them across the border.
In Colombia's northeast, where many Venezuelans have ended up, rival armed groups control illegal border crossings and wreak havoc on civilians with killings, intimidation, sexual violence and recruit children as soldiers, according to a new report by NGO Human Rights Watch.
The report focuses on the impoverished Catatumbo region, where armed groups -- including the National Liberation Army (ELN), the Popular Liberation Army (EPL), and former members of the Revolutionary Armed Forces of Colombia (FARC) -- wage bloody battles for control not only between each other but also on Colombian soldiers. The area is an important one for coca cultivation, according to the United Nations Office on Drugs and Crime.
More than 100 civilians were killed there by the battling groups in 2018, according to the HRW report, which cites United Nations figures. Some Colombian and Venezuelan children have been coerced into either joining groups or enforcing their rules. The report claims that in March, ELN fighters "visited a rural school in Catatumbo to try to convince children to join their ranks." Some children have been threatened for allegedly cooperating with rival groups, according to HRW.
One mother told HRW that local fighters offered her son guns and a motorcycle to work for them, and later warned the family to avoid interacting with government soldiers.
As local authorities struggle to keep up with a rising number of homicides in the area, armed fighters are policing territories and local populations.
Tens of thousands of people have left the region since 2017, according to Colombian government figures cited in the report. Yet Venezuelans continue to flood in from across the border. Earlier this year, Reuters reported that internally displaced Colombians in the area "can be seen begging for food alongside" Venezuelan migrants and refugees.
Colombia has welcomed vast numbers of refugees from Venezuela since its economic downturn began accelerating. On Monday, Colombian President Iván Duque announced in a series of tweets that the country would grant citizenship to more than 24,000 children born to undocumented Venezuelan parents -- any child born since August 19, 2015.
"Colombia, once again, is showing the world that even in the midst of fiscal constraints, with a per capita income of less than $8,000 dollars," Duque said, "we also know how to make out of fraternity, a feeling of solidarity." However, he also called for the international community to end Venezuela's crisis, which has created an estimated exodus of four million people.
Colombia's Ministry of Defense and Ministry of Foreign Relations did not respond to a request for comment.