Actress Vanessa Marquez – a regular on the hit medical drama ER, and who accused co-star George Clooney of black-listing her when she alleged harassment on the show, a charge Clooney denied – was killed in an officer-involved shooting at her home in Pasadena on Thursday. Marquez was 49.

The news was confirmed via Twitter by the LA County Sheriff's office:

Officers were conducting a welfare check at the request of Marquez's landlord when she allegedly pulled out a "BB type" replica gun, causing officers to open fire. She was later pronounced dead at a LA hospital.

When the shooting happened, "there was an LA County mental health clinician here with the officers," Lt. Joe Mendoza of the LA County Sheriff's Office said. "They began to communicate with her, she became very uncooperative, and during that contact she armed herself with a handgun, she pointed it at the officers and an officer-involved shooting occurred."

Marquez was undergoing some medical problems and appeared "gravely disabled" to the officers, Mendoza said. Not much else is known on the incident right now.