Mobile County Sheriff Paul Burch said Tuesday his agency will “hunt down” the people who shot and killed a 15-year-old teenage girl during a rolling shootout on Interstate 165 Monday.

Burch’s comments come after a second day of an investigation that included shutting down the I-165 exits to Bay Branch Road on Tuesday, and the recovery of gun shell casings that indicated the shooters were firing semi-automatic weapons.

“We will stay on this and hunt down these people like the thugs they are that indiscriminately shoot into vehicles and houses hitting the innocent,” Burch said.

A 9-year-old was also shot during the shootout that occurred around 3 p.m. and was taken to a hospital where he was listed in stable condition.

It was the second time the 9-year-old had been shot during an incident in which a shooter’s intended target was his 18-year-old brother.

The 15-year-old who died was a cousin to the 9-year-old and 18-year-old.

All three were inside the SUV seated in the middle row. In the backseat was a 4-year-old child who Burch described as the sibling of the 15-year-old who was killed.

Burch said his agency has not identified the shooter.

He said the mother of the intended victim “is being less than cooperative with us, and I find that very alarming.”

The Sheriff’s Department has not yet released the name of the 15-year-old victim.

The agency is asking the public, if they have any information about the shootout, to contact them at 251-574-8633 or to leave information on their online Crime Tip form.