Tempe police believe four juveniles and a 19-year-old man were responsible for three street robberies.
As of Monday,police had arrested all but one of them.
Just after 10 p.m. on Nov. 28, three of the teenagers - ages 19, 15 and 12 - stopped a 17-year-old riding a motorized skateboard down Broadway Road near South Los Feliz Drive, striking him in the head and knocking him to the ground, Tempe police Sgt. Steve Carbajal said.
They continued to hit the 17-year-old as he lay on the ground, he said.
The three fled the area after taking the skateboard and other property from the victim, police said.
After learning of the incident, Tempe police ACTION Team officers found Brandon Bailey, 19, and the two teens near the 1800 block of Broadway Road.
The three eventually admitted they were responsible for the robbery, police said.
After further questioning, the three told police about an unrelated Nov. 26 robbery in the 1800 block of Palmcroft Drive.
A 16-year-old was also involved in that incident, they told police. He was soon arrested.
As police investigated the robberies, they found items that didn't belong to the two victims. They determined another robbery had occurred July 9. Another 15-year-old was found to be involved in this incident.
He will likely be arrested soon, Carbajal said.
Police have determined the robberies were not gang-related and the motivation for them is unknown, he said.
All were arrested on suspicion of aggravated robbery.