A 17-year-old student has shot and wounded two school administrators at a high school in Denver in the US.

The shooting happened after a handgun was found during a daily search of the boy that was being conducted because of behavioural issues, authorities said.

Suspect Austin Lyle remained at large following the shooting at East High School and was wanted for attempted homicide. The gun he used was not immediately recovered, said Denver police chief Ron Thomas.

Police issued an alert linking Lyle to a red 2005 Volvo X90 with Colorado plates and offered a reward up to 2,000 dollars for information on the case.

The shooting happened just before 10am in an area away from classrooms as the student was undergoing a search as part of a “safety plan” that required him to be patted down daily, officials said.

One of the administrators was critically injured and was undergoing surgery in hospital. The second victim was in a stable condition, Mr Thomas said. Both victims are male.

Mr Thomas said police know where the suspect lives and were confident they would apprehend him.

“He obviously is armed and dangerous and willing to use the weapon, as we’ve learned this morning,” Denver mayor Michael Hancock warned as police searched for the suspect.

Earlier this month students from the school skipped class and joined a march to demand stricter gun laws, following the death of a fellow student who was shot while sitting in a car near the school, which has about 2,500 students.

There were no school resource officers on campus at the time of Wednesday’s shooting, Mr Thomas said. But following the shooting, Denver Public Schools superintendent Alex Marrero said two armed officers will be posted at East High School through to the end of the school year.

In June 2020, amid a summer of protests over racial injustice following the murder of George Floyd, Denver Public Schools became one of the districts around the US that decided to phase out its use of police officers in school buildings.

That push was fuelled by criticism that school resource officers disproportionately arrested black students, sweeping them into the criminal justice system.

Gun violence at schools has become increasingly common in the US with more than 1,300 shootings recorded between 2000 and June 2022, according to researchers from the Naval Postgraduate School and Centre for Homeland Defence and Security.

Those shootings killed 377 people and wounded 1,025, according to a database maintained by the researchers.

Students from East High School had been scheduled to testify on Wednesday afternoon before the Colorado Legislature on gun safety bills.

“This is the reality of being young in America: sitting through a shooting and waiting for information just hours before you’re scheduled to testify in support of gun safety bills,” said Gracie Taub, a 16-year-old East High School student and volunteer with Students Demand Action in Colorado.

“Our school experience should not be completely shaped by gun violence,” she added.

The suspect in Wednesday’s shooting had transferred to East High School from another district, Mr Marrero said. Officials did not reveal why the student was being searched daily.

Mr Marrero said safety plans for students are enacted in response to “past educational and also behavioural experiences”, adding that it is a common practice throughout Colorado’s public schools.

But daily pat-downs are rare, said Matthew McClain with the Colorado School Counsellor Association, and Franci Crepeau-Hobson, a University of Colorado Denver professor specialising in school violence prevention.

“Clearly they were concerned,” said Ms Crepeau-Hobson. “I can’t imagine they’d do that if there wasn’t a history of the kid carrying a weapon for whatever reason.”

East High School was placed on lockdown as police investigated the shooting.

Hundreds of parents lined up along a road near the school, with the scene sealed off by police.

Some parents and students vented frustration over violence at the school as they surrounded the police chief. Others argued about the causes of the violence.

Wednesday was also the second anniversary of 10 people being shot and killed at a supermarket in Boulder, Colorado.

White House press secretary Karine Jean-Pierre said she was not sure whether President Joe Biden had been briefed on the school shooting, but said: “Our hearts go out to the families of the two school administrators in Denver today, and to the entire school community.”

She repeated Mr Biden’s called for stricter gun laws, including bans on assault-style weapons and high-capacity magazines, and for Congress to “do something” on gun control.