(CNN) A gunman killed two people in the parking lot of a Walmart in Duncan, Oklahoma, on Monday morning before turning the gun on himself, police Chief Danny Ford said.

The Duncan Police Department said a man and woman had been killed in a car parked at the Walmart. Both were in the front seats, while the other man was found on the ground on the driver's side of the vehicle, near the back door, Ford said.

Witness Aaron Helton told CNN affiliate KOCO that two victims were killed in the parking lot. While Helton said the gunman fatally shot himself after a bystander confronted him with a firearm, Ford said that could not be confirmed

Helton told the station he heard nine shots. Video captured by CNN affiliate KOKH showed a red vehicle with what appeared to be six bullet holes in the windshield.

"It appears several rounds were fired into the car, and a handgun was recovered at the scene," Ford said, estimating that nine shots were fired.

Read More