A student victim is dead and the male gunman is also deceased after shots were fired Tuesday at Reynolds High School in Troutdale, Ore., east of Portland, Troutdale Police Chief Scott Anderson said.
Officers responded to the school shortly after 8 a.m.
Tactical efforts have concluded, according to CBS affiliate KOIN. The situation is stabilized, according to police.
"I'm very, very sorry for the family and for all the students and everyone who will be impacted by this tragic incident," Anderson said at a brief news conference Tuesday.
Parents are being reunited with their children and most students have already been evacuated from the school, officials said.
"This is a very tragic day, one that I had hoped would never, ever be part of my experience," Reynolds School District Superintendent Linda Florence said at the conference.
Multiple agencies responded to the scene, KOIN reported. The gunman was found dead as police arrived. Police didn't immediately identify the slain student.
Sixty police and sheriff's units were on hand, as well as 19 medical personnel. A LifeFlight helicopter landed in a nearby field, according to the station.
KOIN reports a student inside the 2,800-student school tweeted just after 9 a.m. that while some students had been evacuated, "most" were on lockdown. One student reportedly told a parent the shooting began in the school's gymnasium, though police have not been able to confirm specific details.
TV news showed students being led from the school with their hands on their heads.
Freshman Daniel DeLong, 15, said while waiting after the shooting that he saw a physical education teacher at the school with a bloodied shirt.
"I'm a little shaken up," DeLong said. "I'm just worried."
He said he was texting friends to make sure they were all okay. "It just, like, happened so fast, you know?" DeLong said.
Citing the school district, KOIN reports that a coach who was teaching a weight lifting class was grazed in the hip by a bullet. At the press conference, police couldn't confirm whether there were other injuries or what kind of gun was used in the incident.
Wednesday is scheduled to be the final day of the school year at the high school, reports KOIN, and seniors were thought to already have completed classes.
Freshman Morgan Rose, 15, said she was hunkered down in a locker room with another student and two teachers. "It was scary in the moment now knowing everything's okay," she said.