Investigators on the scene of a deadly shooting by San Mateo County Sheriff's deputies. (CBS)

HALF MOON BAY (CBS SF) – An 18-year-old woman was shot and killed by a sheriff’s deputy in San Mateo County on Tuesday night.

Deputies responded to a violent an potentially armed woman at the Moonridge Housing Complex on Miramontes Point Road east of state Highway 1 around 9:20 p.m., San Mateo County Sheriff’s spokeswoman Rebecca Rosenblatt said. The building houses many of the areas agricultural workers.

A deputy who arrived at the scene and confronted the woman, Yanira Serrano-Garcia, and shot at her after a growing fearful, Rosenblatt said.

According to Garcia’s aunt, the 18-year-old suffered depression and had stopped taking her medication.

Emergency crews were called to the scene and pronounced the woman dead, she said.

Garcia’s cousin, Saul Miramontes, said they called 911 for help, but he never expected his cousin, Yanira, to be shot dead.

“I feel bad for her for what happened,” he said. “I don’t know why this officer couldn’t understand what was going on through her life, or could have done at least something better than try to take her life away, you know?”

Miramontes said he was told that Garcia did have a knife.

The San Mateo County coroner’s office was called to the scene in addition to detectives from the sheriff’s office, Rosenblatt said.

Deputies were not injured in the incident, according to Rosenblatt.

The San Mateo County deputy involved in the shooting has been named as Menh Trieu, a nine-year veteran of law enforcement, who had been with the department for a couple of years.

Family friend Carlos Ramirez was one of many people going in and out of the Garcia’s home Wednesday morning as a priest prayed with her parents.

“I just don’t get it. This girl is 18-years old, she’s a girl. I’m not saying that girls are weak, but if she’s not all mentally there; she doesn’t know where to put that knife, she doesn’t know your vital points to kill you,” he said.

A joint investigation into the shooting is being conducted by the San Mateo County sheriff’s and district attorney’s offices.

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