Whoever sprayed a north Birmingham adult birthday party with bullets this weekend did so with fully automatic gunfire, killing four people and wounding 10 others.

It’s become a common scene in Birmingham and beyond.

Where police investigators used to retrieve a dozen or less shell casings from a crime scene, they now are tasked with picking up and logging dozens — if not hundreds.

The culprit, experts say, are Glock switches – also known as auto sears or a button or a giggle switch – which can unleash 20 rounds per second or 1,200 rounds a minute.

“Switches have permeated the firearm possession of young people,’’ said Marcus Watson, the Special Agent in Charge of the Bureau of Alcohol, Tobacco, Firearms and Explosives in Birmingham.

“Most of the urban areas have been hit with an unbelievable amount of these devices that have turned a semi-automatic gun, and sometimes a rifle, into a fully automatic machine gun that wreaks absolute havoc in the neighborhoods,’’ Watson said.

“There’s no place that device has a purpose in the United States,’’ he said. “We’re cracking down.”

Northern District of Alabama U.S. Attorney Prim Escalona, flanked by federal, county and city leaders including Birmingham Police Chief Scott Thurmond and Mayor Randall Woodfin, on Thursday announced the launch of Operation Flip the Switch, an initiative targeting the illegal switches – which are machine gun conversion devices.

“The violence that we are seeing in our communities is flagrant and unacceptable,’’ Escalona said. “Machine gun conversion devices have no place in our community.”

“Though small in size, a switch is deadly, and a lot of innocent people can be injured with pull of the trigger,’’ she said. “It’s almost impossible to control the spray of those bullets.”

Escalona said switches are present throughout Alabama’s northern district – even in Tuscaloosa and Huntsville – but are most prevalent in Birmingham and Jefferson County.

A switch is about one inch long and can be made of metal or plastic and can be made on 3D printers.

The device fits onto the back of a handgun and allows the user to switch between semi- automatic gunfire and fully automatic gunfire.

“When they first started, we were seeing them imported, even from other countries,’’ Escalona said. “Now we have started seeing them manufactured here with the 3D printer.”

Under federal law, the device itself is considered to be a machine gun, not just a gun accessory.

“No one is permitted to own, possess, or use a switch,’’ Escalona said.

The maximum sentence for a conviction in switch cases is 10 years in federal prison. There is no parole in the federal system, and suspects can and will be held from the time of arrest until trial.

“If you are convicted, you will not serve your time in Alabama,’’ Escalona said. “So it’s a way to take people out of the community to give that community a chance to rebuild.”

Alabama has no state law governing switches, so the cases are prosecuted federally with a maximum sentence of 10 years in federal prison.

Woodfin and Thurmond said state legislators need to create laws so the problem can be tackled on more than one front.

Roughly 40 cases have been prosecuted in the Northern District of Alabama in recent years, but Escalona said under Operation Flip the Switch, they are now prioritizing switch cases, as well as increasing training for law enforcement officers so they know what to look for and who to call if they encounter a switch.

Educating the community is also going to increase under the operation, again letting residents know what to look for and who to call.

Crime Stoppers of Metro Alabama is part of the initiative, and tipsters who lead authorities to switches or 3D printers manufacturing the devices could get anywhere from hundreds to thousands of dollars in reward money.

Woodfin said crime is down double-digits in Birmingham, though homicides have increased.

So far this year, there have been 91 homicides in the city. At this time last year, there had been 79 slayings.

“There is a subset of people in our community who don’t care about our community,’’ Woodfin said. “We’ve got to take those people off the streets.”

“They’re riding around with these Glock switches. Their intent is to inflict massive amounts of casualties and carnage,’’ he said. “Too many people are being killed – even this past weekend.”

Birmingham police have taken about 1,000 guns of the streets in the first half of 2024. Since Woodfin took office, the police chief said, they’ve confiscated about 17,000 guns.

The mayor acknowledge that the criminals likely aren’t watching or reading the news, but said their mothers, grandmothers, family and friends are.

“So, our conversation with them is very direct or simple – your son, your loved one, your grandson will have to sit down for 10 years if they’re riding around with this,’’ he said. “I’m quite confident that information will get out.”

Asked why more people don’t come forward, Thurmond had this to say: “I’m going to be real honest. If it doesn’t affect them, they don’t care.”

“There are a lot of people who watch what goes on in our city and other parts of the state, but if it doesn’t directly affect them, they just don’t care,’’ he said.

Escalona said switch prosecutions are unique in that they are evidence-bases cases which typically don’t require witnesses to testify.

“This is one way,’’ she said, “you can anonymously help your community without subjecting yourself to danger or retribution.”