PANAMA CITY, Fla. (AP) — The ex-convict who calmly held a school board at gunpoint and then began randomly firing had circled the date on a calendar found in his mobile home, evidence he had been planning the attack for some time, police said.

The shooting at the Bay District board meeting was not "a spur of the moment thing," Panama City Police Chief John Van Etten told The Associated Press. Police also found anti-government paraphernalia at Clay A. Duke's home, but the chief didn't provide details.

"He was obviously was not happy with our government," Van Etten said.

Video of Tuesday's meeting show Duke, 56, complaining about taxes and his wife being fired by the district before shooting at close range as the superintendent begged, "Please don't."

Minutes earlier, the room had been filled with students accepting awards, but no one was hurt except Duke, who shot himself after exchanging fire with a security guard, police said.

"It could have been a monumental tragedy," Superintendent Bill Husfelt said. "God was standing in front of me and I will go to my grave believing that."

Video shows Duke rising from his seat, spray-painting a red V on the wall, then waving a 9mm Smith & Wesson handgun and ordering everyone to leave the room except the men on the board. They dove under the long desk they had been sitting behind as he fired at them.

Duke's motivation was still murky Wednesday. He rambled to the board about tax increases and his wife, but also apparently created a Facebook page last week that refers to class warfare and is laced with images from the movie "V for Vendetta," in which a mysterious figure battles a totalitarian government.

The school board was in the midst of a routine discussion when Duke walked to the front of the room.

"We could tell by the look in his eyes that this wasn't going to end well," Husfelt told the AP.

Husfelt was calm as he tried to persuade Duke to drop the gun, but Duke just shook his head. The only woman on the board, Ginger Littleton, had been ordered out of the room too, but she sneaked back in behind him and whacked his gun arm with her large brown purse.

"In my mind, that was the last attempt or opportunity to divert him," Littleton said.

Duke, a large, heavyset man in a dark pullover coat got angry and turned around. She fell to the floor as board members pleaded with her to stop. Duke pointed the gun at her head and said, "You stupid b----" but he didn't shoot her. She's not sure why.

She joked during a Wednesday press conference that her three daughters asked "'Are you just stupid? What were you thinking?' I don't have an answer for that."

After several minutes, video showed Duke slowly raising the gun and leveling it at Husfelt, who pleaded "Please don't, please don't."

Duke shot twice at Husfelt from about 8 feet away and squeezed off several more rounds before district security chief Mike Jones, a former police officer, bolted in. Police said Wednesday the pair exchanged at least 14 shots, with Jones hitting Duke four times, felling him. Duke then shot himself fatally in the head. Police said he had at least 25 more rounds of ammunition.

Somehow, no one else in the small board room was injured in the clash that lasted several minutes. Husfelt said at least two rounds lodged in the wall behind him.

In Duke's brief exchange with the board, he said his wife had been fired from the northern Florida district, but never told Husfelt or the board who she was or what she did. Members promised to help her find a new job, but Duke just shook his head. Husfelt told Duke he didn't remember his wife but would have be responsible for her dismissal, so the board members should be allowed to leave.

"He said his wife was fired, but we really don't know what he was talking about," Husfelt told the AP on Tuesday at his Panama City home.