MADISON, Wis. -- Madison police investigating a report of an armed robbery surrounded a stopped Madison Metro bus, detained four passengers and recovered a fake gun Tuesday afternoon.

Police said that at about 1:45 p.m. Tuesday, officers were sent to the 7400 block of Mineral Point Road after two teens reported being robbed at gunpoint. Police said the crime took place outside and involved four suspects -- one with a handgun.

Police said both victims provided good suspect descriptions, and police determined the suspects had had likely boarded a Madison Metro bus.

Police stopped the bus near the intersection of Mineral Point Road and Gammon Road, near West Towne Mall.

"An officer observed the bus, (and) they thought they saw those individuals on the bus. The bus was stopped; those individuals were taken into custody without incident. There was a facsimile weapon that was located on the bus," said Sgt. John Rife, of the Madison Police Department.

Police said four suspects onboard the bus, whose ages range from 15 to 20, were taken into custody for questioning.

Police said money and electronics were taken during the robbery, and one suspect was found carrying at least one stolen item.