A man angry about being sued for unpaid child support opened fire with an AK-47 (search) assault rifle outside a courthouse, killing his ex-wife and a man trying to help the couple's adult son.

The gunman, 43-year-old David Hernandez Arroyo Sr., was killed Thursday afternoon in a gun battle with officers a few miles away after wounding his son and three law enforcement officers, one critically.

The son had been acting as a mediator between his parents, police said.

Police estimated that Arroyo, who had a history of spousal abuse and weapons violations, shot 50 rounds in the historic town square. He was wearing a military flak jacket and a bulletproof vest.

"He definitely came well-armed and prepared," police Chief Gary Swindle said. "We do understand there had been some threats made by him the previous week."

But the attorney representing Maribel Estrada, 41, said he doesn't believe she thought her ex-husband was dangerous. Estrada worked at a meat packing plant in Tyler and raised a 17-year-old and a 6-year-old with the help of her eldest son, Joshua Wintters said.

The other victim, Mark Alan Wilson, 52, was credited by authorities with saving the life of David Hernandez Arroyo Jr., who was listed in fair condition at a hospital with leg wounds. A sheriff's deputy, Sherman Dollison, 28, was in critical condition after being shot in the liver, lungs and legs; a sheriff's lieutenant and a Tyler police detective were treated and released.

"One of the deputies at the scene said if it hadn't been for Mr. Wilson," said Sheriff J.B. Smith, "the son would be dead."

Friends who visited the son in the hospital Thursday night said he told them that his father was always open about having a collection of weapons.

Aurea Seanez said the son told them, "And look now, he used them on us."

Wilson, a gun enthusiast who once owned a shooting range, intervened after Arroyo killed his ex-wife, witnesses said. Swindle, the police chief, said Wilson shot at Arroyo several times but his rounds weren't penetrating the armor.

"They traded shots, missing each other, and then the gunman hit Wilson and Wilson went down," Tyler Morning Telegraph publisher Nelson Clyde III said in Friday's editions of the newspaper. Clyde watched the shooting from a nearby restaurant.

"The gunman walked up to Wilson and shot him while he was on the ground," Clyde said. "I couldn't believe what I was seeing. It was sickening."

Estrada and Arroyo divorced in January 2004 after 22 years of marriage. Wintters wouldn't say why the two divorced.

Tyler, the seat of Smith County, is a city of about 86,000 located about 95 miles east of Dallas. Tyler calls itself the "Rose Capital of the Nation" and attracts about 100,000 visitors each October to the Texas Rose Festival (search).