There have been no reports of injured students, and there is no longer an active threat, the Olathe Police Department tweeted around noon (1 p.m. ET).
The shooting happened in an office area, the agency said.
Police are on site, and the building is secure, Olathe Public Schools said in a tweet.
“If your loved one was injured, you would have already been contacted by the police department,” the school district tweeted.
Police asked parents looking to reunite with their child to meet at the nearby Family Video or Frontier Park.
The school, which has about 2,000 students, is located about a 30-minute drive southwest of Kansas City.
This is a developing story and will be updated.