Two students at the exclusive St. Albans School in the nation's capital were detained for questioning Wednesday after police responded to a report that a man with a gun had parked a vehicle on campus.
There was no violence, and the campus soon returned to normal.
Metropolitan police were called to the boys school shortly after 8 a.m. and ordered a "shelter in place" for students at the school while a search began.
The neighboring Washington National Cathedral also was locked down as a precaution.
"Once they located the vehicle they did observe what appeared to be a weapon," said Assistant Police Chief Patrick Burke. Authorities did not immediately enter the car, but brought explosives-detecting dogs to the scene while waiting for a search warrant.
Burke told CNN it was "a long gun in the back. We're not sure if it's an actual, functional weapon, [or a] BB gun - we're not positive at this point."
Police then located the driver and a passenger, and said both are students at the school. "One person has been taken into custody," Burke said.
"Charges are pending at this point. It depends on what we find in the car."
Burke said he had no indication that the boys were plotting violence, and he declined to characterize their temperament when police apprehended them for questioning.