HOUSTON – John Barnes, the Santa Fe Independent School District police officer, was injured in Friday's shooting at Santa Fe High School.

Barnes was shot in the arm and the bullet hit an artery. He was taken in critical condition by LifeFlight helicopter to The University of Texas Medical Branch in Galveston.

Officials said Barnes lost a lot of blood at the scene, and underwent surgery that started around 9:20 a.m.

Surgeons repaired a blood vessel near his elbow and are working on repairing the injury to the bone, officials said.

Hospital officials said Barnes will go to surgical intensive car, then his family will be able to see him.

Doctors said many officers and former colleagues have shown up to support Barnes.

Here's what we know about John Barnes:

The 49-year-old is a retired Houston police officer.

Barnes started as a jailer with the Tarrant County Sheriff's Office in 1991.

The following year he was appointed a peace officer with the Tarrant County Sheriff's Office.

Barnes left TCSO in August 1993.

He was sworn in with the Houston Police Department in November 1994.

Barnes started his career at the Southwest Patrol and worked there until 2005, when he moved into investigations.

According to HPD Chief Art Acevedo, Barnes is "known for his tireless work in Houston Metro Internet Crimes Against Children Task Force.

He retired in January of this year.

The day after his retirement from HPD, Barnes began work as a police officer with Santa Fe ISD.