D.C. police arrested two men Wednesday morning after two people were robbed of their bicycles in Northwest Washington, the sixth attack linked to a series of holdups in which stun guns were used, according to authorities.

D.C. Police Chief Cathy L. Lanier said the investigation is continuing but “we do not know if this is tied to the others.”

Police identified the suspects as Michael Moore, 19, of Northeast, and David Ashton, 18, of Northwest. Each was charged with robbery.

The two are charged in an attack that occurred about 2 a.m. in the 4000 block of Georgia Avenue NW in Petworth. Officer Anthony Clay, a police spokesman, said three men joined in the robbery and demanded the victims’ bicycles, wallets and cellphones.

Clay said one of the men appeared to be holding a stun gun — the victims reported seeing sparks from a red metallic object pointed at them — but the weapon was not used to harm them. Clay said officers arrested two of the three men a short time later.

Police said in a statement that they are searching for the third man, who was armed with the stun gun. He is described as a black male standing 6 feet to 6 feet 2 inches tall and weighing between 150 and 160 pounds. He has brown eyes and long back dreadlocks and was last seen wearing black pants and a black jacket, according to the statement.

Police said in court documents that they retrieved the victims’ bicycles. Both victims were Hispanic and did not speak English very well, according to the court documents. Police have said that many of the previous victims were also Hispanic.

Two people were robbed Sunday — a newspaper delivery man in Capitol Hill whose car was taken and a man in the 2100 block of 10th St. NW who police said was stunned in the back and knocked down as he walked through an alley.

Three other people were robbed last week near the Washington Convention Center in Mount Vernon Square. In one case, police said one assailant was armed with a stun gun and another with a handgun. In most cases, wallets and cellphones were stolen. One man was shocked and repeatedly punched and required hospital treatment.