LOS ANGELES — A gunman accused of killing eight people in a California hair salon was in a bitter custody battle with his ex-wife, who was among the dead, reports said Thursday as details of the carnage emerged.

Police said Scott Dekraai, 42, "knew his intended victim" when he opened fire with a handgun in the upmarket Salon Meritage in Seal Beach, south of Los Angeles, at lunchtime Wednesday.

Survivors of the massacre recounted the moment the burly former tugboat worker -- who suffered from post-traumatic stress disorder after a boating accident -- entered the packed salon.

"I just kept hearing boom, boom, boom, boom," a woman who gave her name only as Cindy told the Orange County Register. "I ran out. I didn't see his face. I just saw the gun in his hand and him shoot," she added.

Dekraai was arrested shortly after the shootings at the hair and nail salon in the quiet resort town, some 30 miles south of Los Angeles. The attack also left one person critically injured.

"This was not a random act of violence," said Seal Beach Acting Chief of Police Tim Olson. "The suspect knew his intended victim," he said, refusing to identify the victims until Friday.

The Los Angeles Times cited witnesses as saying Dekraai specifically targeted his ex-wife, Michelle Fournier, a hair stylist described as "fun loving" but caught in a bitter dispute with her ex husband.

Court papers showed that Dekraai's doctor Ronald Silverstein had diagnosed him with stress disorder in September 2008, following an accident in which a deckhand was killed and Dekraai permanently disabled, the Times said.

The court documents, filed as part of divorce proceedings, showed that Fournier reported her husband had become mentally unstable.

In the February 2007 accident Dekraai witnessed the death of a young deckhand, crushed by a rope attached from the tug to a barge. Dekraai himself was left permanently disabled, according to his former employer.

"Up until the accident he was heavy into fishing and watersports like surfing and boogie boarding," said Don Ashley, owner of Pierpoint Landing in Long Beach, where Dekraai worked for 10 years.

"The last four or five years, he was pretty miserable," he added.

Dekraai split from his wife in 2007, and the couple fought over custody of their son, who was eight at the time of their separation, and to whom he was very attached.

"Michelle (had a) fun-loving, outgoing personality," said Ashley. "She was a hairdresser, and you pretty much have to be outgoing to be a hairdresser."

He insisted that Dekraai was happy before the accident.

"Everybody loved him. If you asked a hundred people and gave me from a scale of one to 10 who would be most likely to flip, he wouldn't have been there," Ashley said.

"He was a nice person. It's hard to say that, and everybody's going to say, 'What the hell, you're standing up for a mass killer,' but he had a nice personality," he added.

The shooting is the deadliest ever in Seal Beach, a small town of 25,000 people where homicides are rare -- although multiple shootings are an all-too-familiar occurrence in the United States.

Among the most notorious is the Columbine massacre in April 1999, when two teenage boys shot and killed 12 students and a teacher.

In April 2007, a student shot 47 people at Virginia Tech, killing 32 before he committed suicide, in the deadliest mass shooting in the United States.