"We know it's a vicious act of violence. Obviously two Jewish facilities, one might make that assumption," Overland Park Police Chief John Douglass told a news conference. The FBI has been called in to help with the investigation, he said.
He was being held at a Johnson County detention center on suspicion of premeditated murder in the first degree and was scheduled to appear in court on Monday afternoon, according to jail records.
The two male victims were identified as Reat Griffin Underwood, 14, a high school freshman, and his grandfather, Dr. William Corporon, family member Will Corporon said in a statement. Both were members of the United Methodist Church of the Resurrection.
Underwood was an Eagle Scout and loved camping and hunting with family, Corporon said. Dr. Corporon had moved to the Kansas City area in 2003 to be closer to his grandchildren.
Two people were shot at, but not hit, the police chief said, adding that it appeared the shooter used a shotgun and possibly other types of guns.
The suspect was taken into custody in the parking lot of a nearby elementary school, Douglass said.
Douglass said he could not confirm reports from witnesses that the suspect had yelled "Heil Hitler" while in the back of the squad car after being taken into custody.
"The suspect in the back of a car made several statements," Douglass said. "We are sifting through and vetting those for accuracy, number one, and number two, we are looking at them for their evidentiary value."
President Barack Obama offered condolences. "While we do not know all of the details ... the initial reports are heartbreaking," Obama said in a statement.
The Jewish Community Center, which is also the site of Kansas City's only Jewish community day school, the Hyman Brand Hebrew Academy, was a hub of activity on Sunday.
Several youth groups were meeting, some people were auditioning in the facility's theater for a music production, and the academy was preparing for a school dance. Many non-Jewish people regularly join in the facility's activities.
The Kansas City area has a Jewish community of about 20,000.