Horseplay, not terrorism, was to blame for an incident that led to the evacuation of a building and a short-lived fall in the U.S. dollar, said Cathy Lanier, commander of special operations for the Washington police department.

One juvenile was in police custody.

A group of "young kids" was in a building near a Washington restaurant "right about peak lunch hour," Lanier said.

"One of them had a personal pepper spray or mace-type personal key chain. Another child grabbed it, I understand, (and) sprayed it in the mall area. It's an irritant so a lot of people felt an immediate burning in the eyes, runny nose, coughing," she said.

Early word that there had been an unspecified chemical incident in downtown Washington briefly hit U.S. stock markets and the dollar, on edge for any sign of attacks this week as the Republican Party holds its convention in New York.

Officials examined 130 people at the scene, treated five and sent one to hospital, said Alan Etter, spokesman for the D.C. Fire Department and Emergency Medical Services.

There were no life-threatening injuries and that the evacuation had ended.

The general manager of a restaurant affected in the incident, Michael Hodges, said the chemical was released in a hallway near his restaurant.

"It went through the ventilation system (into the restaurant) and made people choke," said Hodges, who manages the downtown Baja Fresh outlet.

Tisha Bai, a law student at George Washington University, said she was outside Baja Fresh when she noticed the spray.