Weather Service says to take cover

• NEW: Officials declare a tornado emergency for Maumelle, Arkansas


• NEW: Buildings were damaged in Quapaw, Oklahoma, a state emergency official says


• Search and rescue operations are under way, a dispatcher says


• Rescuers are in an area where a concrete wall crashed onto a car, an official says

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(CNN) -- Witnesses spotted a twister in the Oklahoma town of Quapaw on Sunday, an emergency official said, as severe weather slammed into parts of the central United States.

Joe Dan Morgan, emergency manager in Ottawa County, Oklahoma, said ambulances had deployed after reports of a funnel on the ground in Quapaw, and rescuers were working in an area where a concrete wall crashed onto a car.

Numerous buildings in the town were damaged, said Keli Cain with Oklahoma Emergency Management.

Kelly Flecks, an emergency dispatcher in Ottawa County, also said a tornado hit the town.

"Search and rescue is underway involving several agencies," she said. "Please tell the public to stay away so they can do their jobs. We can't confirm anything else at the moment.

Quapaw is in the northeastern part of the state, near the borders with Kansas and Missouri.

Also Sunday evening, a tornado emergency was declared for Maumelle, Arkansas, the National Weather Service said. Maumelle is just northwest of Little Rock in central Arkansas.

Storm spotters were tracking a confirmed tornado with reports of damage, the Weather Service said. A tornado emergency is issued when a storm is producing a life-threatening, confirmed tornado capable of significant destruction.

CNN's Dave Alsup, Matthew Stucker and Sean Morris contributed to this report.