Four teenagers — the youngest just 13 years old — have been charged with robbery, conspiracy and wearing a disguise after a series of three swarmings in south Ottawa on Thursday night, according to Ottawa police.

The other suspects are 15, 17 and 18.

In each swarming a single victim was surrounded, and property was taken in two of the cases, police said.

Police said "a significant number of frontline resources were deployed," including the K-9 unit, after swarmings were reported on a pathway between Colliston Crescent and Cedarwood Drive, near the intersection of Chartley Private and Colliston Crescent, and in Sandalwood Park around 8 p.m.

The 13-year-old was also charged with robbery, wearing a disguise and possession of a weapon in an Oct. 21 swarming around Spadina and Bayswater avenues.

All four suspects are expected to appear in court today.

Police said additional charges are possible as the robbery unit continues to investigate recent robberies that occurred in both the Heatherington Road and Bayswater Avenue areas.

Anyone with information is asked to call police at 613-236-1222, ext. 5116 or Crime Stoppers toll-free at 1-800-222-8477.