For the first time, the California Department of Public Health released the names of the facilities that have been impacted.
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According to the data, 258 locations across the state have reported one or more positive COVID-19 cases in residents or staff members.
Officials said the list is a snapshot representing 86% of the state's 1,224 skilled nursing facilities that have reported data within the last 24 hours.
More than half of the facilities, 148, are located in Los Angeles County.
But two facilities in Tulare County - the Redwood Springs Health Center in Visalia and Lindsay Gardens Nursing and Rehabilitation in Lindsay - are also part of the list.
RELATED: Visalia nursing home reports 2 more residents die from COVID-19; 156 test positive for virus
So far, 106 patients and 50 staff members at Redwood Springs have tested positive for the coronavirus, making up roughly 50% of Tulare County's COVID-19 cases.
Ten of those residents of the facility have died from the virus.
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A current employee of the nursing home claimed the number of cases could have been minimized if management had acted sooner.
At Lindsay Gardens, 13 residents and 3 employees have so far tested positive for the virus.
RELATED: 16 people at Lindsay nursing center test positive for COVID-19
The new data drew a quick response from union leaders, who called it a "clarion call to action for all of us."
"This deadly pandemic is targeting our most vulnerable elders. Those charged with caring for them -- low wage workers, almost always women -- are walking into infection zones without the most basic of protections," said April Verrett, president of Service Employees International Union Local 2015, in a statement.
Verrett also called for "immediate testing" of everybody in those facilities as well as daily reporting on infection rates from all skilled nursing homes in California.