By Da Lin

GILROY (CBS SF) — Evidence markers littered a backyard. Bottles remained scattered on a makeshift table. Nearby investigators searched for clues Saturday evening in an attempt to unravel why a large Gilroy Halloween party ended in deadly gunfire.

One person was killed, three others were injured — two of the partygoers suffering from life-threatening injuries.

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Officers got a 911 call at 12:55 a.m. Saturday reporting the shooting at the Las Animas Ave. residence of Gilroy city councilwoman Rebeca Armendariz.

Investigators said Armendariz hosted the large Halloween party in her side yard. In the aftermath of the violence, crime scene technicians could be seen taking photos of shell casings scattered on the ground. One technician even used a metal detector to look for casings that might have been hidden under fallen leaves and dirt.

The shooting has left the neighborhood stunned.

“We heard the gunshots, a bunch of them,” said Linda Leighton, who lives in an RV parked near Armendariz’s house. “Boom, boom, boom. Boom, boom, boom. And then we heard people screaming. So we all came running out.”

Xitlali Gonzalez lives across the street from the councilwoman. She told KPIX about 80 people attended the party, most of them appeared to be teenagers and young people.

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“It was really surprising because she’s always been a really good neighbor,” Gonzalez said. “She never throws parties. So it was kind of unexpected.”

Police said a fight broke out between some partygoers and led to the shooting.

“Most of them were running and running away, getting into their cars and going,” said Leighton. ” But there was lingering, a couple of people, after the police were done (interviewing them). They said, I guess it was an older boy, from what I understood, an older boy had some kind of altercation with them.”‘

Investigators haven’t said what the fight was over or the exact motive. They did not release any suspect information or any additional details about the victims.

“It’s sad,” said neighbor Joanne Camp. “It really is. It’s sad that people can’t have I guess more respect for one another and have more peace and have fun.”

The councilwoman declined an interview with KPIX 5, but released a statement that read in part, “I am thankful that my family and I, who live on Las Animas, were not hurt in this tragedy, and I pray for those whose loved ones have been touched by what has occurred. In the meantime, we are giving our full cooperation to the Gilroy police department in this investigation. Our primary concern is for the individuals impacted and their families.”

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Armendariz was elected to the Gilroy city council last year. And before that, she was on the planning commission.