The six teens represented Burundi, a small country in East Africa, in the inaugural FIRST Global robotics competition, competing alongside teams from more than 150 other countries.
Metropolitan Police Department spokeswoman Aquita Brown said two were seen leaving the US for Canada. Police could not confirm they are still in Canada and did not provide updates on the other four youths.
There are no indications of foul play, police said.
The State Department directed questions to DC law enforcement.
The six teens were last reported seen at the location of the event -- DAR Constitution Hall on 18th St between C Street and D Street in northwest DC -- the Metropolitan Police Department
"On the night of July 18, FIRST Global learned the adult mentor of Team Burundi was unable to find the group of six students of the team who participated in the 2017 FIRST Global Challenge," the competition's organizers said in a statement.
The mentor is identified in police reports as Canesius Bindaba. Bindaba stated that "he does not know where (they) could have went," the police reports said.
DC police tweeted names, ages, descriptions and photos of the six missing individuals. There are four boys and two girls, ranging in age from 16 to 18, according to the tweets.
The teens were reportedly last seen at 5 p.m. ET, police said. An itinerary of the event says that the robotics competition was scheduled to end at 5:30 p.m., and closing ceremonies were to run from 5:30 p.m. to 7 p.m.
FIRST Global President Joe Sestak called the police to report the students as missing, according to the organization's statement, and "proper follow on reports have been submitted to the police who are investigating the case.
"Security of the students is of paramount importance to FIRST Global. FIRST Global ensures that all students get to their dormitories after the daily competition by providing safe transportation to the students staying at Trinity Washington University who are always to be under close supervision of their adult mentor and are advised not to leave the premises unaccompanied by the mentor."
Anyone with information is urged to contact authorities at 202-727-9099.
The competition attracted significant national attention after six girls on the Afghan team were denied visas for the competition, but later allowed
to travel when President Donald Trump intervened. Ivanka Trump attended
the event Tuesday, meeting with the Afghan girls.
A country of about 10 million people, Burundi
has endured years of unrest, with an estimated 300,000 people dying in a civil war that was fought from 1993 to 2003.
In recent years, Burundi, and its capital, Bujumbura, have been marked by social instability, political tensions and economic hardship.
"The political situation in Burundi is tenuous, and there is sporadic violence throughout the country, including frequent gunfire and grenade attacks by armed groups," a June 23 US State Department travel warning said.
Last month, a UN official briefed the Security Council
about the deteriorating humanitarian conditions and large swaths of the population on the move, about 209,000 inside the country and more than 400,000 to neighboring nations.
"Mass displacement continues, due to natural hazards, food insecurity and socio-political factors," Assistant Secretary-General Tayé-Brook Zerihoun said.
"Three million people in Burundi are in need of humanitarian assistance. Nearly 2.6 million others experience acute food insecurity, with over 700,000 in need of emergency food assistance."