Three 19-year-old men were charged in U.S. District Court on Monday in connection with a string a of violent carjackings throughout the Twin Cities this summer.

A joint investigation by the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), and local police tied Delaney N. Harris of Chicago to a June 1 carjacking in downtown Minneapolis, in which a man leaving his vehicle was reportedly thrown to the ground and stripped of his car keys at gunpoint, charges say.

Witnesses told Minneapolis police that Harris had been holding a red plastic cup just before the attack. Officers found the cup and later matched fingerprints and DNA to Harris, authorities said.

The assault occurred the same day Harris posted bond for a burglary charge related to the theft of i-Robot vacuums from a Maple Grove Best Buy, court records show.

In a similar incident Aug. 25, Joshoamei Richardson, AKA "Yoshi," and James B. Williams Jr., reportedly brandished a firearm and threatened to kill a motorist outside a St. Paul Subway restaurant before making off with his Dodge Charger, according to Monday's indictment. The men, both of St. Paul, were charged with aiding and abetting carjacking and related firearms offenses.

Williams and Richardson also face aggravated robbery charges in Ramsey County in the incident. Juvenile court records identify Richardson as founding member of EBK, a St. Paul Street gang.

Williams was also charged with aggravated robbery last month after an Oct. 12 incident in which he allegedly pressed a gun into the back of a man walking to work, demanding his phone and wallet.

Law enforcement say the incidents represent a troubling surge of violent carjackings throughout the Twin Cities this year, which has left residents on edge. Teenage suspects tend to approach victims on the street, sidewalk or parking lot — often while they're distracted with routine tasks. In the past seven weeks, Minneapolis police have logged at least 76 carjackings or attempts.

"We will not hesitate to hold accountable individuals who perpetrate this type of violence in our communities," U.S. Attorney Erica H. MacDonald said in a statement.