LEBANON, Pa. (AP) — Two young boys were playing with kittens in their backyard when shots rang out at a home in eastern Pennsylvania, killing both children and a young man who was the apparent target, authorities said Thursday.

An adult and a teen have been charged in the shooting, and police are seeking a third suspect.

Alex Torres Santos, 22, and a 16-year-old male have each been charged with three counts of criminal homicide, Lebanon County District Attorney Pier Hess Graf said. They also face aggravated assault, conspiracy and weapons offenses related to Tuesday’s shooting in Lebanon, a small city in an agricultural region roughly 70 miles (110 kilometers) northwest of Philadelphia.

A third male is still being sought and will likely face similar charges, authorities said. Santos was on house arrest for several unrelated charges and was wearing an ankle monitor at the time of the shooting.

The violence stemmed from “a previous argument,” authorities said Thursday, but further details on the motive were not disclosed.

The shooters apparently targeted 19-year-old Joshua Lugo-Perez, while 8-year-old Jesus Perez-Salome and 9-year-old Sebastian Perez-Salome were both in the home’s back yard, authorities said. All three victims lived at the home where the shooting occurred, but Lugo-Perez was not related to the two boys.

The younger boy was pronounced dead at the scene. His older brother and Lugo-Perez both died a short time later at hospitals.

A 33-year-old neighbor who was wounded by a stray bullet underwent surgery and remains hospitalized, but he is expected to recover, authorities said.

Lebanon Police Chief Bret Fisher said officers responded to the home shortly after 10 p.m. Tuesday after a report of shots fired.

A Lebanon County SWAT team arrested Santos at his apartment Wednesday. Authorities said he attempted to flee the residence but was captured there, while the teenage suspect was later arrested at a nearby apartment where he was trying to hide. Ammunition and multiple firearms were found at the apartment where Santos was arrested, authorities said.

Graf, the district attorney, said Thursday that the suspects could potentially face the death penalty, but that decision has not yet been made. It wasn’t clear Thursday if either suspect had retained an attorney.