LOWELL — A Lowell teen has been charged alongside another juvenile in a case where a BB gun made to look like a semiautomatic handgun was allegedly used during the violent armed robbery of a U.S. Postal Service mail carrier in Billerica.

The Middlesex District Attorney’s Office, the Billerica Police and the U.S. Postal Inspection Service said in a joint press release on Friday that the 14- and 15-year-old defendants are charged with armed robbery and assault with a dangerous weapon in connection with the Nov. 12, 2024, incident, during which a mail carrier was struck in the face and forced to hand over a postal mailbox key.

The postal mailbox key has since been recovered.

Authorities said the investigation showed the two juveniles traveled by train from Lowell to Billerica on the morning of the incident with the intent to target a mail carrier.

After arriving in the neighborhood near the town center, they allegedly spotted the victim and followed him before attacking him at about 1:30 p.m.

One teen allegedly struck the carrier in the face, while the other, holding the BB gun, demanded his postal key. The victim handed it over, and the pair fled.

Detectives later recovered the suspects’ outer clothing and the weapon in the area.

Detectives identified the teens through witness interviews, surveillance footage and several search warrants executed over the course of months, authorities said. Their names have not been released because of their ages.

The stolen mailbox key was recovered about two months after the robbery.

The Billerica Police announced on Nov. 19, 2024, that they had arrested the 15-year-old Lowell boy believed to be one of the assailants. In Friday’s press release, news of the 14-year-old’s arrest was revealed.

Authorities said that both teens have been arraigned and were released on personal recognizance with conditions to stay away from and have no contact with the victim. They were also ordered to have no contact with each other and to not possess any dangerous weapons.

State Police assigned to the Middlesex District Attorney’s Office and USPIS assisted in the investigation.

The November 2024 robbery was followed just two months later by another mail-related case in Billerica.

In early January 2025, the Billerica Police arrested Brayden Moran, 18, of Lowell, and two juveniles after detectives conducting surveillance near the Boston Road post office said they saw two masked teens approaching multiple mailboxes.

Police said the trio was caught soon after, and detectives located a USPS “arrow key” in their possession, along with stolen checks and other items of evidence.

It is not immediately clear if these cases are related.

Follow Aaron Curtis on X @aselahcurtis, or on Bluesky @aaronscurtis.bsky.social.