17-year-old Shawn L. Godwin and 17-year-old Alexander Jones were taken into custody on Sunday. 18-year-old Artez D. Sheppard remains at large.
The robbery happened Saturday morning near Midway Estates. The victim - a man in his 30s - had his wallet and Iphone stolen.
A relative of Godwin watched news reports about the robbery and saw that he had an unknown Iphone.
When questioned by family, Godwin admitted he had gotten it from a Hispanic male.
The relative's growing concern made her contact police.
Arriving officers took Godwin into custody after he showed them the victim's phone and wallet.
An investigation revealed that Jones and Sheppard also took part in the robbery.
Jones was arrested Sunday morning as well and a BB gun, which resembled a black semi-automatic handgun, was turned over to police.
Police later learned the gun was the weapon allegedly used during the crime.
Jones and Godwin were released into the custody of their parents, pending arraignment.
Sheppard is still at large. Police say he may possibly live in the Burton Village Apartments in Rehoboth.
Anyone with information is asked to contact Delaware State Police Troop 7 at 302-644-5020 or Delaware Crime Stoppers at 1-800-TIP-3333. Information may also be provided via the internet at www.tipsubmit.com.