Prosecutors will seek the death penalty for the man they called a "methodical and merciless killer" who stormed through a salon and killed eight people.

Orange County District Attorney Tony Rackauckas said Friday that Scott Dekraai has been charged with eight counts of murder and one count of attempted murder.

Rackauckas choked up several times during an emotional news conference while saying the rampage was triggered by a long-running custody dispute that Dekraai had with his ex-wife, Michelle Fournier. She was one of the people fatally wounded.

"In a selfish, cruel act of senseless violence, eight innocent people were murdered," Rackauckas said.

He said Dekraai, 41, arrived at Salon Meritage in downtown Seal Beach on Wednesday carrying three weapons and dressed in body armor. At one point he stopped to reload before he continued killing people.

"For almost two minutes Dekraai shot victim after victim, executing people by shooting them in the head and chest," the district attorney said.

Rackauckas said the bloodbath was triggered by Dekraai's desire for revenge against his ex-wife, who he believed was interfering in the raising of their 8-year-old son.

"That little boy's a victim," the prosecutor said. "Now his mother has been murdered, and he has to grow up knowing that his dad is a mass-murderer. So what kind of sick, twisted fatherly love might that be?"

Fournier had recently told friends and family and said in court documents that she feared for her safety as Dekraai became more and more unbalanced.

Dekraai suffered post-traumatic stress disorder from a 2007 tugboat accident that mangled his leg and left a colleague dead but his marriage to Fournier was falling apart even before that, and the court battle over their son was still raging Wednesday before the shooting.

Several hundred attended a prayer service at a church across from the salon on Thursday night and more than 1,500 showed up with candles at a vigil in the parking lot of the shopping center where the salon stands. About a half-dozen therapy dogs, wearing green vests embroidered with names like Anise and Riley, moved through the crowd providing comfort to mourners.

The quaint, sun-splashed town of Seal Beach, with its Main Street of vintage shops, restaurants and boutiques, has had only had one homicide in the previous four years.