SKIATOOK, Oklahoma - A man, apparently angry over a fence dispute, fatally shot three men before committing suicide in front of police officers, authorities said.

Howard Hawthorne of Tulsa, Oklahoma, who lived next to where the shooting occurred, is believed to have shot his neighbor, Anthony Graham, 44, Graham's son Joshua Leforte, 21, and another man, Dewayne Goodwin, Tulsa County Sheriff's Capt. Fred Cotton said Thursday.

Hawthorne fired on the three men with a shotgun as one pulled up a fence post with a tractor, said Tulsa County Undersheriff Brian Edwards.

Skiatook police officers responding to a call about gunshots saw bodies on the ground and Hawthorne on a riding lawn mower, Cotton said. As they pulled up, Hawthorne shot and killed himself.

"This is a horrendous deal," Edwards said. "This is one of the most disturbing crime scenes I've seen."

Hawthorne had complained to sheriff's deputies earlier Thursday that his neighbors had moved or destroyed his fence, Cotton said. They went to his home, advised him of what he could do about his complaint and left.

"He seemed satisfied and thanked the deputies," he said.

About 30 to 40 minutes later, the sheriff's office and the Skiatook Police Department received an emergency call about shots fired, he said.

Investigators were trying to determine Goodwin's connection to the other two victims, he said.

Deputies are interviewing people who witnessed the shooting as they drove past, Edwards said.