3 Killed, 1 Wounded in 2 O.C. Shootings : Violence: Back-yard attack leaves husband dead, wife critically hurt; man kills girlfriend, self.

Deadly violence erupted at two Orange County homes Monday, when first gunmen stormed into a back-yard birthday party and opened fire just after midnight, and then hours later a young man turned a gun on his girlfriend and then himself.

The unrelated incidents left three people dead and a 21-year-old teacher’s aide clinging to life at a local hospital.

In the first incident, Joel Davalos, 21, of Santa Ana died and his wife was critically injured when gunmen barged into a small, back-yard barbecue at 12:29 a.m. at 316 S. Flower St. in Santa Ana and began firing.

“Without any warning, one or more of the suspects began shooting,” Police Lt. Robert Helton said. “Both Mr. and Mrs. Davalos were struck in the stomach.”

Davalos died instantly in the hail of gunfire while his wife, Sylvia, was critically wounded and remained at Western Medical Center-Santa Ana on Monday night.

“There is no apparent reason for the shooting . . . no provocation whatsoever,” Helton said. “There’s nothing that indicates a gang scenario, and we have absolutely zero explanation at this point as to why these guys came into the yard and started shooting.”

Another couple at the party and their year-old daughter, who was asleep at the time, were not injured. They declined comment Monday but told friends and family that seconds before the incident, Sylvia Davalos said she had seen a shadow lurking behind a bush.

The only other couple there, Mary Davalos and Jay Dole, were away from the house at the time of the shooting to buy beer for the party. Before leaving, Mary Davalos, the slain man’s sister, said she and her boyfriend had heard loud gunshots.

“We all listened to it for some minutes, and it stopped, so we didn’t think anything of it and went to the store” Mary Davalos, 20, said.

The second incident Monday involved a 23-year-old Fullerton man who shot and killed his 20-year-old girlfriend and then fatally shot himself in the head, Fullerton police said.

Police said Tuu Sam, 23, and his girlfriend had been arguing at about 3:15 p.m. in an upstairs apartment in the 4100 block of Carol Drive.

The woman, who lived in Inglewood, was shot twice in the chest and once in the head, said Police Detective John Minn. Her name was not disclosed pending notification of relatives.

According to police, the couple had been dating about seven months. Police did not know the motive for the shooting or what caused the argument.

Police said they found a .38-caliber handgun in the apartment. In all, five shots were fired, based on the number of casings police found on the apartment floor. Apartment manager David Alexander, 32, said only Sam and his girlfriend were in the apartment at the time of the shooting. He said Sam rented the apartment with two older brothers.

“As long as I lived here, I don’t remember the police having to come down here for anything . . . I never had any problems with those guys,” Alexander said. “They would mind their own business. This blows me away.”

A neighbor, Ronda Jarrott, 24, said she saw Tuu Sam in a nearby laundry room about 1 p.m. Monday. “He said, ‘Hi.’ And everything seemed fine.”

But neighbors in the Santa Ana neighborhood where the first shooting occurred Monday said violence there is not so uncommon. Residents in the downtown neighborhood, largely composed of small duplexes, said gunshots are often heard in the area and drug-dealing is sometimes visible on the streets.

“It happened so fast,” Dole said Monday afternoon. “We were gone for not more than 15 minutes, and we came home and it was all over.”

News of the shooting had traveled quickly among family members Monday, as Joel Davalos’ brother was expected to arrive in Santa Ana on Monday night from Mexico. Other family members were drawn to the house that Joel and Sylvia Davalos had shared to talk about the outgoing couple who had celebrated their second wedding anniversary just last week.

Joel Davalos, like his wife, was working toward a teacher certificate. He worked as a teacher’s assistant in language at Andrew Jackson Elementary School in Santa Ana, and she as a special education assistant at Willard Intermediate School.

They both loved children and wanted eventually to become teachers, family members said. Joel “got the job with the school (as an aide) almost as soon as he finished high school,” his 24-year-old sister Luci said. “He couldn’t wait to help children.”

Monday morning, the school district dispatched psychologists to Jackson and Willard to counsel teachers and students who knew the victims. The couple had worked in the school district since 1990, officials said.

“Joel was just a wonderful teacher’s aide, well-liked by everyone,” Jackson Principal Gloria Roelen said. “When he told me he wanted to be a teacher, I was very pleased. He would’ve been a wonderful teacher . . . and a fine model for students.

“I was . . . looking forward to him someday being on my staff as a teacher. What happened is just a tragedy, and at the school, we’re just trying to deal with it.”

At Willard, Sylvia Davalos “is loved by all who know her,” Principal Howard Haas said. “She’s a really compassionate lady, and she has the prayers of all of us here today.”

Following 1991’s record 59 homicides in Santa Ana, Davalos is the city’s eighth murder victim in 1992, police said.

Times staff writers Donnette Dunbar, Eric Young and Ajowa Ifateyo contributed to this story.