Six Burundi teenagers have been reported missing after taking part in an international robotics competition in Washington DC. A police spokesperson said authorities “do not have any indication of foul play” as the investigation continues into what happened after the group attended the FIRST Global Challenge robotics competition with students from 157 nations.

Teams of high school students from more than 150 countries took part in the competition organized by FIRST Global, a U.S.-based non-profit that organized the competition which was designed to encourage careers in math and technology.

Police reports indicated that the four boys and two girls were last seen in the early evening of July 18th in northwest DC after which their adult mentor was unable to locate them. FIRST Global informed the police later that day.  All six members of the robotics team Audrey Mwamikazi, 17, Nice Munezero, 17, Don Charu Ingabire, 16, Kevin Sabumukiza, 17, Richard Irakoze, 18, and Aristide Irambona, 18 reportedly have one-year US visas.

The DC police have said that Ms Mwamikazi and Mr Ingabire are in Canada because they were spotted crossing the border but no details have been released about how they got there or why.  Canada’s Border Services Agency said it could neither confirm nor deny that the pair entered Canada.  DC police also said the other four teenagers seem to be in a safe place, but police are not reporting any further details.

The Republic of Burundi,has a population of 11.2 million people and is a landlocked country in the African Great Lakes region of East Africa.  It is bordered by Rwanda, Tanzania and the Democratic Republic of the Congo.  It has been plagued by instability for decades with bouts of ethnic cleansing and ultimately two civil wars and genocides during the 1970s and again in the 1990s left the country undeveloped and its population as one of the world’s poorest.

Burundi continues to experience civil unrest after a failed coup in 2015.  The U.S. State Department issued a travel warning in late June about the African nation, advising Americans of “political tensions, political and criminal violence, and the potential for civil unrest.”  The warning also stated that rebel forces, ex-combatants and youth gangs from the Democratic Republic of Congo reportedly crossed into Burundi and attacked and kidnapped civilians; armed criminals have ambushed vehicles.

There have also been reports of human rights abuses as well. According to the UN, over 300,000 people fled the country since 2014 due to violent gangs from Congo and disappearances and killings allegedly committed by Burundian security forces.