HUNTSVILLE — A 10-year-old boy opened fire on his 15-year-old sister, striking her multiple times, then shot and killed himself at a residence in west Walker County on Thursday night.

The Walker County Sheriff’s Office said the shooting occurred at about 9 p.m. Thursday at home in the 200 block of Duke Road when Coby Tucker walked into his sister Ashley Tucker’s bedroom and began firing a small caliber handgun. The boy then turned the gun on himself.

Both victims were taken by Life Flight to Hermann Memorial Hospital in Houston, where Coby Tucker was pronounced dead on arrival. Ashley Tucker underwent surgery for multiple gunshot wounds and was listed in critical but stable condition Friday.

The mother of the victims, Maura Tucker, was home at the time of the shooting but did not see what transpired. She said she heard multiple gunshots and, after finding out what happened, called 911.

Officers did not have a chance to interview the parents or the injured girl, so at this time they do not have a motive for the shooting. The children’s father, Curtis Tucker, was a work at the time of the incident. The family has no other children.

“We have not been able to talk to the girl because she was in surgery this morning,” Detective Greg Williams said. “It is still early in the investigation, and we are not sure why this happened.”

After investigating the crime scene, deputies said they believe that Coby Tucker got access to the handgun from a locked safe in the home. No charges have been filed in the shooting.

“There is no reason for us to believe that this was a case of negligence by the parents,” Walker County Sheriff Clint McRae said. “The firearm was in a secure safe, but the boy was somehow able to gain access. This is a terrible tragedy that happened and our thoughts are with the family.”

Coby Tucker was a student at Huntsville Intermediate and Ashley Tucker is a sophomore at Huntsville High School. A spokesman for Huntsville Independent School District said Friday that counselors at both campuses were prepared to support students and staff during this difficult time.

“Upon learning of this tragedy, the district’s immediate response was to ensure that our counseling staff at both of the campuses were prepared and available to provide any support necessary to our students and staff members today,” HISD officials said in a prepared statement. “Huntsville ISD has already made preparations for extra counselors and professionals to be available at all campuses on Monday should the need arise.”