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Teenage twin brothers have been charged with possessing firearms illegally altered to fire automatically and with fleeing police after leaving the funeral of a slain friend this week in Minneapolis.

According to charges filed in Hennepin County District Court, the 18-year-old brothers, Quantez and Cortez Ward, were seen riding in a vehicle from which police seized three handguns outfitted with devices called auto-sears — commonly known as "Glock switches" — that can turn the weapons fully automatic.

The brothers did not have lawyers as of Wednesday afternoon, but they were scheduled to make their initial court appearances Thursday, when the court could assign them attorneys.

Minneapolis police and Hennepin County Sheriff's personnel were conducting surveillance at a funeral for 15-year-old Santana Jackson on Jan. 17 when they saw the brothers arrive, according to the charges. Authorities had learned earlier that they would attend and likely be carrying handguns modified to fire fully automatic.

Jackson, who was suspected of gang activity, was shot to death on New Year's Eve in an apparent robbery-gone-wrong in Minneapolis. Another boy, 16, was wounded but survived.

Police said the twin brothers were in a black Jeep driven by 21-year-old Muhnee Bailey, who drove off after officers stopped the SUV at the Winner gas station on West Broadway. But the Jeep crashed, and Cortez Ward was arrested at the scene. His brother and Bailey were taken into custody after a brief foot chase, the charges said.

Authorities said they seized three modified handguns from the vehicle; DNA testing is pending.

In a follow-up interview, Bailey admitted to fleeing police but denied knowing about the guns found in the vehicle, according to the charges.

Authorities and crime prevention workers say the modified firearms have been showing up at crime scenes with frightening frequency in recent months.

Regular semiautomatic guns fire one round each time a trigger is pulled, but an automatic gun will shoot continuously until the trigger is released. The illegal conversion devices can be quickly and easily be fitted onto a Glock handgun by removing the polymer slide cover plate, a process that requires little technical expertise. They are readily available on the Dark Web or made at home on 3-D printers, law enforcement officials say.

This week, prosecutors charged Javeyon D. Tate, 21, with playing a role in the fatal New Year's Eve encounter. Alleging that Tate drove Jackson and the second boy to the scene, knowing that they intended to rob a man under the guise of carrying out a shoe sale, authorities charged him with one count each of first-degree riot and first-degree aggravated robbery.

It is not clear whether the man who shot the two boys will be charged or whether he had legal authority to carry a weapon.