Washington County authorities have arrested two teenagers who they say are responsible for a string of aggravated robberies at restaurants in the eastern Twin Cities suburbs.

With the help of Oakdale police, deputies from the Washington County Sheriff's Office apprehended an 18-year-old man and a 16-year-old boy who are suspected of robbing a Starbucks coffee shop at 3156 Century Av. in Mahtomedi on Monday.

Authorities searched an Oakdale residence and the suspects' and found money and other evidence that linked them to three other armed robberies of eateries in Woodbury, said Sgt. Andrew Ellickson of the Washington County Sheriff's Office.

The men admitted their involvement in the holdups of two Subway restaurants and an ice cream shop earlier this year, said Capt. Kris Mienert of the Woodbury Police Department. The suspects are being held in the Washington County jail,

The first robbery came on Jan. 3, when two robbers hit the Subway restaurant in the Valley Creek Mall at 1740 Weir Drive. The robbers -- one toting a handgun and the other a knife -- came through the door a few minutes before closing and took cash from a register and safe.

The same men are believed to be responsible for a similar robbery on Jan. 25. In that heist, two men came into the Subway at 8470 City Centre Drive just minutes before closing and ordered the two employees to open the safe and empty the cash drawer. The robbers displayed a gun and a knife during the robbery, Mienert said.

Oakdale police said that the two men are suspected of holding up the Quizno's at 1053 Helmo Av. at gunpoint on Jan. 27.

And at 8:52 p.m. on Friday in Woodbury, one robber displayed a handgun at the Marble Slab Creamery at 8144 Coller Way in Tamarack Village.

Mienert said Woodbury police will request formal charges on both subjects for three counts of aggravated robbery.