A former college football standout at the University of Oregon has been credited with tackling an armed student at a high school before anyone was injured.

Keanon Lowe, a football and track coach and a security guard at Parkrose High School in Portland, Oregon, told reporters as he was leaving a police interview late on Friday he was tired but relieved at the outcome, The Oregonian/OregonLive reported.

There are no other suspects. Police declined to release the student's name and said they were still trying to determine if he fired any shots. Police spokesperson Sergeant Brad Yakots declined to confirm Mr Lowe's reported involvement.

"I'm just happy everyone was OK," Mr Lowe said as he walked out of the school about four hours after the incident, according to The Oregonian/OregonLive. "I'm happy I was able to be there for the kids and for the community."

Mr Lowe did not reply to messages sent on Twitter or LinkedIn.

Mass shootings in America Show all 8 1 /8 Mass shootings in America Mass shootings in America Camden shootings – 1949 Howard Unruh killed 13 people, including three children, during a 12-minute walk through his neighborhood on September 6, 1949, in Camden, New Jersey, when he was 28 years old. The incident became known as the "Walk of Death". Unruh was found to be criminally insane and died in 2009 after a lengthy illness at the age of 88, following 60 years of confinement. Alamy Mass shootings in America University of Texas tower shooting – 1966 Charles Whitman killed 17 people and injured 31 others in Austin, Texas. After stabbing his mother and wife the night before, he headed to the University of Texas, where he opened fire on people in the campus and streets from the observation desk. He was shot dead after a policeman and civilian reached the scene. Austin History Center, Austin Public Library Mass shootings in America Easter Sunday Massacre – 1975 James Ruppert killd 11 family members in his mother's house, which included his mother, brother and his wife, as well as their eight children. He used a magnum, two handguns and a rifle. Mass shootings in America Wilkes-Barre shootings – 1982 Former prison guard, George Banks, shot dead 13 people in Pennsylvania, including five of his own children. AP Photo/Times Leader Mass shootings in America Wah Mee massacre – 1983 Three men, Kwan Fai Mak, Wai-Chiu Ng, and Benjamin Ng, killed 13 people who were in Seattle's Wah Mee gambling club. YouTube/KIRO 7 News Mass shootings in America San Ysidro McDonald's massacre – 1984 James Huberty killed 21 people and injured 19 others after he walked in a McDonald's in San Diego. He was shot dead by a sniper after 78 minutes of him entering the restaurant. Alamy Mass shootings in America Palm Sunday massacre – 1984 Ten people were shot dead from handguns at close range in a New York home. A baby girl was the only survivor after convicted dealer, Christopher Thomas, shot three women, one teenage girl and six children in their Brooklyn home. Thomas was convicted of manslaughter and cleared of murder. He was released from prison after 32 years. Mass shootings in America Edmond post office shooting – 1986 Patrick Sherrill, a postal worker at the Edmond post office in Oklahoma, killed 14 co-workers and injured 6 others, before he shot himself. Oklahoma Highway Patrol Collection

Parkrose school district superintendent Michael Lopes Serrao said in a letter to families on Friday evening that before the incident two students had informed a staff member of "concerning behaviour" by that student.

Security staff then responded, found the student and quickly disarmed him, he said.

"Thanks to their heroic efforts all students and staff are safe," Mr Lopes Serrao wrote.

Mr Yakots, the police spokesperson, said the first responding officers found the gunman being detained by the staff member in the hallway. A firearm was recovered at the school, he added.

Parkrose was evacuated and a nearby middle school was on lockdown for several hours as the investigation unfolded. The high school students were bused to a nearby parking lot where they were reunited with their parents.

The outcome was "the best-case scenario, absolutely," Mr Yakots said. "The staff member did an excellent job by all accounts, (and) our officers arrived within minutes and went right in."

Students recounted how the student entered their government class in the school's fine arts building — separate from the main building — just before noon. Mr Lowe had been in the classroom earlier looking for the student, whom other students identified as an 18-year-old senior at Parkrose.

About 10 minutes before the end of class, the student appeared in the doorway in a black trench coat and pulled out a long gun from beneath his coat, senior Justyn Wilcox, who was also in the room, told The Oregonian/OregonLive.

The student did not point the gun at anyone, student Alexa Pope said.

Support free-thinking journalism and attend Independent events

Students fled out the back door because the gunman was blocking the main doorway.

"As I was running, I was just like, Lord don't let this be it," Ms Pope told the newspaper.

In college, Mr Lowe was a star wide receiver at the University of Oregon, playing from 2011 to 2014. He caught 10 touchdown passes in his college career and had nearly 900 receiving yards. He also saw playing time on special teams.

After college, he worked as an offensive analyst for the San Francisco 49ers and as an analyst for the Philadelphia Eagles.

Mr Lowe began working at Parkrose last year as the school's head football and track and field coach, according to his LinkedIn profile. Before that, he worked for his high school alma mater, Jesuit High, where he earned state defensive player of the year as a defensive back and was a standout sprinter.

Students, parents and co-workers lauded Mr Lowe's actions on Twitter, calling him a hero. Several also noted that the school's prom, scheduled for Saturday, was still on.

Olivia Katbi Smith wrote on Twitter that she coaches track with Mr Lowe at Parkrose and was not surprised to learn what he did.

"As soon as I heard what happened I knew it was him because he would do anything for these kids. It was surreal to be waiting for my athletes behind caution tape today, but might have been much worse if not for Keanon," she wrote.

Lopes Serrao said the student with the gun will not be returning to school and that school will resume on Monday as usual with an enhanced security presence.