Police arrested the suspect in the parking lot of a nearby elementary school shortly after the shootings, which happened minutes apart at around 1 p.m. in the Kansas City suburb of Overland Park.
Authorities declined to release the names of the suspect or the victims, pending the notification of their relatives. At a news conference, Overland Park police Chief John Douglass said the suspect is in his 70s, is not from Kansas and wasn't known to area law enforcement before the attacks. He also said there is no indication that the suspect knew any of the victims.
"Today is a sad and very tragic day," Douglass said. "As you might imagine we are only three hours into this investigation. There's a lot of innuendo and a lot of assertions going around. There is really very little hardcore information."
Douglass said the suspect made several statements to police, "but it's too early to tell you what he may or may not have said." He also said it was too early in the investigation to determine whether there was an anti-Semitic motive for the attacks or if they will be investigated as hate crimes. The Jewish festival of Passover begins Monday.
"We are investigating it as a hate crime. We're investigating it as a criminal act. We haven't ruled out anything. ... Again, we're three hours into it," he said.
Douglass said the first attack happened in a parking lot behind the Jewish Community Center of Greater Kansas City. The attacker shot two males. One died at the scene and the other died at a hospital. He said the suspect then drove to the nearby retirement community, Village Shalom, where he shot and killed a female. The gunman also shot at two other people during the attacks, but missed them, Douglass said.
Douglass said a shotgun was used in the attacks, and that investigators are also trying to determine if a handgun and assault-style rifle may also have been used.
Police officers were also sent to other Jewish facilities in the area immediately after the shootings, the police chief said.
"We're not going to give the specifics. ... I can tell you as much as this. Immediately when we learned we had an active shooter we dispatched vehicles to secure and surveil all the active Jewish facilities in the city and other religious institutions which are not Jewish," he said.
The suspect was taken to the Johnson County Detention Center. Johnson County District Attorney Stephen Howe, who attended the news conference along with Barry Grissom, U.S. Attorney for Kansas, said it was too soon to know when the suspect would appear in court.
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.
"Everyone participating in JCC programming has been released to their homes," the center posted later Sunday.
There was a heavy police presence at the campus, which spans several acres in an affluent area of Johnson County. Police had also taped off the entrance to Village Shalom on Sunday afternoon, and several patrol cars and a crime scene unit van were parked in front.
St. Louis area resident Kristy Straeb, 47, said her sister-in-law Stacie Ventimiglia was at the center's pool with a friend and four little girls under the age of 7 for a swimming lesson, which ended about 12:45 p.m. Straeb said they decided at the last minute to get the girls showered.
"They had just gotten the four babies naked, and somebody yelled into the family locker room, 'We have an active shooter situation. You need to get safe,'" Straeb said.
The women got into a cubby area and were "ready to push the little girls into 4 empty lockers," Straeb said. She noted that the women and their children were not harmed and left the center about 2:45 p.m. Sunday.
President Barack Obama released a statement expressing his grief over the attack.
"While we do not know all of the details surrounding today's shooting, the initial reports are heartbreaking," Obama said. "I want to offer my condolences to all the families trying to make sense of this difficult situation and pledge the full support from the federal government as we heal and cope during this trying time."
Kansas Gov. Sam Brownback, in a statement, vowed to seek justice for those who were killed.
"My heart and prayers are with all those who were affected by today's events. We will pursue justice aggressively for these victims and criminal charges against the perpetrator or perpetrators to the full extent of the law."
Michael Siegal, chair of the Jewish Federations of North America, also said in an emailed statement that "no community should have to face a moment such as this one."
"Today, on the eve of Pesach, we are left to contemplate how we must continue our work building a world in which all people are free to live their lives without the threat of terror," he said.