On a day when thousands of marathon participants ran through District streets, police officers also did some fast footwork, racing after a clutch of suspected robbers in Northwest and arresting three of them.

Police said the incident began about 2:45 p.m. in the 700 block of Columbia Road NW, when as many as four people used a knife in a holdup.

As the robbers fled, officers patrolling nearby spotted them and “gave chase on foot,” a police official said. Three people were arrested and charged with robbery, the official said.

The incident came as police have sought to stop a wave of street robberies, many involving efforts to grab smartphones.

A cellphone was seized Friday night at 12th and E streets NE, and a suspect was arrested nearby, police said. Arrests were also reported in “snatch” robberies Saturday on Capitol Hill in the 700 block of Pennsylvania Avenue SE, and downtown in the 600 block of H Street NW.