Indiscriminate firepower has littered crime scenes across the Twin Cities this summer with dozens of shell casings, broken glass, and at times, human carnage.

Bullets have hit neighborhood homes, the 4th Precinct in north Minneapolis, and businesses downtown.

“I thought it was a hailstorm,” Norris Vorasan said after the automatic gunfire terrorized his apartment building next to the Nicollet Diner in July.

That shooting set a new record this summer for the most rounds fired at one scene: 177.

Police and federal agents say the level of firepower is being inflated by a small, nickel-sized device called a switch that turns handguns into automatic machine guns.

Combined with an extended magazine, a switch allows a gunman to fire off dozen of rounds with one squeeze of the trigger.

“The mere number of rounds that are coming out of these fully automatic firearms are very scary. It’s very dangerous,” said Sgt. Adam Lepinski with the gun investigation unit at the Minneapolis Police Department.

“The rounds go everywhere and could hit anybody potentially,” Lepinski said.

While the number of shootings typically rises with the temperature during summer months, investigators say the prevalence of automatic gunfire is making them significantly more dangerous.

“Now it’s 30, 40, 50 shots fired and 20, 30, 40, 50 shots fired back, which is exponentially worse,” said William McCrary, Special Agent in Charge of the St. Paul Field Division of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).

5 INVESTIGATES started tracking the prevalence of automatic gunfire back in July as the violence continued to frustrate law enforcement, politicians, and families.

From Memorial Day to Labor Day, there were more than 200 cases involving a firearm in Hennepin County, according to a review of court records.

Nearly 50 of those cases involved an extended magazine, a machine gun, or an illegal switch.

“The trend line is hockey stick up,” said McCrary.

McCrary said they’ve seen switches manufactured on 3D printers.

Just this week, a 25-year-old man was charged with using a printer to make numerous switches and automatic machine guns out of his home in Minneapolis.

According to court records, Aaron Cato had the parts mailed to him from Taiwan. 

“We’re tracking down not just the possessors but their sources of supply,” McCrary said.

A switch by itself is considered a machine gun under federal law.

“I think for young people, it’s a new toy that they’re trying out,” said Lisa Clemons, a former Minneapolis police officer and now a well-known community activist.

Clemons found herself caught in the middle of a shootout this summer while driving on West Broadway Avenue in north Minneapolis. It happened right before a City Council meeting where she spoke and relived the nightmare.

“My kids are traumatized to death. They almost died in my car,” she said, as her voice trembled.

Clemons started A Mother’s Love eight years ago to help families and kids affected by gun violence.

And now that includes her own.

“I’m telling my kids, ‘Get down, get down on the floor. Get down, get down, get down.’ It was surreal,” she said. “For me, it’s emotional. To see how wide my children’s eyes are open at that moment.”

Clemons believes the continuing increase in automatic gunfire will have a devastating impact on the Twin Cities.

“It’s gonna bring living hell down on Minneapolis and Minnesota,” she said. “It will bring living hell to this city in this state. And we are not ready for it.”