Overland Park city spokesman Sean Reilly said two people died at the Jewish Community Center of Greater Kansas City campus in Overland Park and one was killed at Village Shalom, which is a retirement community that is several blocks away from the center.
A 15-year-old boy who was brought from the scene is in critical condition, Overland Park Medical Center spokeswoman Christine Hamele said.
One person of interest is in custody, Overland Park Fire Department spokesman Jason Rhodes said.
Authorities didn't immediately release further details about the shootings, including whether the center and retirement community were targeted because of religion.
Overland Park police received multiple calls at about 1 p.m. Sunday, public information officer Gary Mason said in a news release. A news conference is scheduled for Sunday evening.
The Jewish Community Center of Greater Kansas City in Overland Park posted on its Facebook page Sunday afternoon that a "shooting incident" happened near its White Theater entrance. A second, later post said that no shooting occurred inside, but in a parking lot.
"Everyone participating in JCC programming has been released to their homes," the center said on Facebook.
St. Louis resident Kristy Straeb, 47, said her sister-in-law was swimming at the center with her children on Sunday and told Straeb that guests were told to hide in the family locker room during the shooting.
There is a heavy police presence at the campus, which spans several acres in an affluent area of Johnson County, Kan. The entrance to the campus is blocked off. Police have also taped off the entrance to Village Shalom, and several patrol cars and a crime scene unit van are parked in front.
Auditions for the KC SuperStar competition were scheduled to be held Sunday at the Jewish Community Center. On Sunday afternoon, the website for KC SuperStar, which is a singing competition for high school students, said the auditions were cancelled.