Two of the six members of the Burundi robotics team, who participated in an international competition this week in Washington, D.C., were seen crossing into Canada and have been reported safe, police confirmed Thursday.

D.C. police said they believe the two teens, identified as Audrey Mwamikazi, 17, and Don Ingabire, 16, left for Canada on their own accord, adding that there was no evidence of foul play. Authorities have not released any further details, the Washington Post reported.

The other four members, including two 17-year-old girls and two boys aged 17 and 18, are also believed to be safe, authorities said. Police declined to provide further information, the Post reported.

Authorities tweeted photos and descriptions of the six teenagers Wednesday. The following day, police identified them as missing persons and asked the public to call with any useful information.

The teens came to the U.S. on one-year visas to compete in the FIRST Global Challenge, an international competition involving more than 150 nations designed to encourage youth participation in math and science. The competition first received national attention after a team of six Afghan girls were denied visas to participate in the competition, until President Donald Trump intervened.

The Burundi team were last seen around 5 p.m. local time, about a half hour before the event ended Tuesday night. FIRST Global President Joe Sestak called the police after the teenagers could be not located.

“Security of the students is of paramount importance to FIRST Global,” the organization’s spokesman Jose Perez Escotto told the NewsHour in an email, adding that representatives are stationed at all times at the dormitories that housed the competition’s participants.

“FIRST Global hired a private firm to provide security at Constitution Hall and also ensured that all students can get safely to their dormitories before and after the daily competition by providing our own transportation to the students staying at Trinity Washington University,” the statement read.

Burundi has been engulfed in a violent unrest since 2015, when the country’s president was re-elected to a third term in office. That election sparked massive protests and led to an attempted coup that same year.

The ongoing civil war in Burundi prompted the State Department to issue a travel warning in late June, warning U.S. citizens of “sporadic violence throughout the country, including frequent gunfire and grenade attacks by armed groups.”

Hundreds of people have been killed and 220,000 have fled the country since the violence erupted, according to the United Nations.