ARLINGTON, Texas (CBSDFW.COM) – Arlington Police said Friday, the 16-year-old Arlington High School student Samuel Reynolds, who was shot and killed Thursday at the apartment complex where he lived, for standing up to a bully at school days earlier.

Samuel Reynolds

One of those teenage suspects is in police custody.

Police say it was just after 4:30 p.m. when Reynolds was shot outside his home, on the grounds of an apartment complex in the 900 block of Benge Drive.

The teen was rushed to a nearby hospital but was pronounced dead a short time later.

The flags have been lowered to half staff at Arlington High School for the 10th grader who police say saw another student being picked on and decided to intervene.

Police say that courage costs him his life.

Reynolds was a sophomore who played on soccer teams around the area.

Police say a 15-year-old who was still in middle school confronted Reynolds in the hallway of the Pinewoods Apartments days after Reynolds stopped the 15-year-old from assaulting another student.

Police say security cameras captured the 15-year-old pulling a .40 caliber gun and shooting Reynolds.

The juvenile suspect was arrested soon after police watched the video.

They are angry that a young man was killed for doing the right thing and that someone gave a 15-year-old access to a handgun.

“That’s something we want an answer for,” said Arlington Police Officer Christopher Cook.  “We are sick and tired of children in our community coming in contact with firearms and possessing them and using them.”

Police say they will prosecute whoever made it possible for the 15-year-old to get his hands on a gun.

Police did not release a lot of information about the alleged shooter because he is underage.

Arlington Police Chief Will Johnson expressed his frustration about the crime on social media, saying, “This senseless act of gun violence has no place in society and our hometown community. This was an emotionally tough case for responding officers, investigators and medics. We will direct our attention to how a young teen suspect accessed a firearm used in the offense.”

Johnson said as the department gathers more information about the young suspect they will pay particular attention to how the boy got his hands on the “firearm used in the offense.”

Police say the suspect and the victim knew each other.

Grief counselors were at Arlington High Friday to offer assistance to students, teachers and staff. Administrators with the Arlington Independent School District say they will remain on the campus as long as needed.

“I’m really sad about him,” said Reynolds friend, Christian Vasquez. “When I found out about it I was gonna cry. Because I… he was one of my favorite friends actually.”

The investigation into the shooting continues and anyone with information is being asked to contact Arlington police at 817-459-5691.

Tipsters wanting to remain anonymous can call the Tarrant County Crime Stoppers line at 817 469-TIPS.

Funeral service and viewing for Samuel Scott Reynolds:

Viewing- Tuesday, February 11th
6-8pm

Funeral Service- Wednesday, February 12th
10am

Moore Funeral Home
1219 N Davis Drive
Arlington, Texas 76012

J.D. Miles contributed to this report.