PULLMAN, Wash. -- Backup Washington State quarterback Tyler Hilinski was found dead Tuesday afternoon in his apartment and authorities are investigating his death as an apparent suicide, according to Pullman police.

Officers went to the apartment to do a welfare check after he missed practice. Hilinski, 21, was found deceased with a gunshot wound to his head — which investigators believe was self-inflicted — with a rifle and suicide note nearby, the police said in the statement released to USA TODAY Sports.

“Pullman Police detectives and the Whitman County Coroner’s Office are conducting a thorough investigation to confirm the suspected cause and manner of death,” the statement said.

Hilinski was a redshirt sophomore and a native of Claremont, Calif. He started the Holiday Bowl in place of Luke Falk, who was injured. It was his eighth appearance of the season and first start.

“We are deeply saddened to hear the news of Tyler’s passing," Washington State head football coach Mike Leach said in a statement. "He was an incredible young man and everyone who had the privilege of knowing him was better for it. The entire WSU community mourns as thoughts and prayers go out to his family."

Added WSU interim athletic director John Johnson: "The tragic news today surrounding Tyler Hilinksi is devastating to all. Tyler was a tremendous individual, great friend and teammate, and he will be deeply missed. Our hearts go out to his family and friends."

Johnson said in the statement that the football team assembled Monday night where news of Hilinski's passing was shared. The school had counseling and psychological staff on hand at the meeting.

"The university will continue to coordinate and provide ongoing counseling care for all student-athletes as long as needed," Johnson said in the statement.

Former Washington State linebackers coach Roy Manning, who recently left for a position at UCLA, tweeted, "Words can't describe what I'm feeling right now. My heart is beyond saddened. Please pray for the family and all of us affected!"

Washington State's players took to social media in reaction to Hilinski's death.

"Ty you were a great teammate, friend, brother anything we needed you to be. You brought smiles to the people around you. I am sorry I could not be there for you when you needed a smile for yourself. Love you man," defensive back Skyler Thomas wrote on Twitter.

Fellow quarterback John Bledsoe, son of longtime NFL QB and former Wazzu star Drew Bledsoe, also wrote on Twitter, "God, let Tyler find peace. Everyone please pray for the Hilinski family tonight. Heaven received a very special person."

Hilinski's most memorable outing came in the second week of the season when he led Washington State from a 21-point deficit in the fourth quarter to beat Boise State 47-44 in triple overtime. Hilinski threw for 240 yards and three touchdowns coming off the bench, and was carried off the field after the victory.

Hilinski attended Upland High in Southern California.

The Associated Press contributed to this report.