Washington State University quarterback Tyler Hilinski was found dead in his apartment in the city of Pullman, authorities said Tuesday. The 21-year-old died in an apparent suicide caused by a self-inflicted gunshot wound.

Pullman police said that a rifle and a suicide note was found next to Hilinski's body. Hilinski's death comes ahead of him starting quarterback job next season for the departing Luke Falk, who was unable to play due to a wrist injury. It remained unclear as to why Hilinski ended his life.

“We are deeply saddened to hear the news of Tyler’s passing,” Washington State head 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.”

Washington State interim athletic director John Johnson called Hilinski’s death devastating and said the football team was informed about the tragedy and met with a psychologist and a mental health counselor.

"The tragic news today surrounding Tyler Hilinski 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.

"Earlier tonight, the football team was brought together and informed of the tragedy. There, they were met by campus and department counseling and psychological services, including athletics' on-staff clinical psychologist and a licensed mental health counselor, along with WSU Athletics medical team. The university will continue to coordinate and provide ongoing counseling care for all student-athletes as long as needed," he added.

Tyler Hilinski Tyler Hilinski #3 of the Washington State Cougars passes the ball against the Michigan State Spartans during the first half of the SDCCU Holiday Bowl at SDCCU Stadium in San Diego, California, Dec. 28, 2017. Photo: Getty Images

Hilinski’s best game of the season came in September against Boise State. Hilinski's brother Ryan posted a tweet shortly after the death was announced, saying: "Please keep my family in your prayers tonight."

Former Washington State linebackers coach Roy Manning, who recently left for a position at University of California, Los Angeles (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!"

Tributes poured in on Twitter from family, friends and coaches of Hilinski.

"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.