Los Angeles County officials, bracing for the possibility of violence, have heightened security as they get ready for perhaps their grimmest task ever--issuing nearly 5,200 layoff and demotion notices today as part of an effort to slash the public health care system to help solve a fiscal crisis.

Efforts to temper the anger and misery that are expected during the biggest downsizing of county government in its history escalated on many fronts Thursday.

The Los Angeles County Sheriff's Department was set to go on a heightened state of readiness this morning, and other law enforcement agencies throughout the county began preparing to respond to any incidents of violence.

Union leaders and county officials haggled throughout the day over precisely how many county jobs could be saved, with the union arguing that it has identified 1,600 contract workers who should be laid off first.

And desperate county supervisors continued lobbying in Sacramento and Washington in a last-minute search for financial assistance to save the health care system from further ravages and to avert at least some of the planned layoffs, which are to take effect Oct. 1, when 28 clinics and six comprehensive health centers are expected to close.

The state Assembly was to begin debating such a bailout package for the county by Thursday evening, but negotiations were under way between lawmakers and Gov. Pete Wilson over the exact dimensions of the financial aid. Wilson returned to California on Thursday after a presidential campaign trip to New Hampshire. Critics faulted Wilson for being out of the state while Los Angeles and Orange counties' financial rescue packages await action in the last hours of this year's legislative session. Wilson, however, blamed Los Angeles county's glum fiscal prospects on a lack of agreement among area lawmakers and county officials.

Against that backdrop, health workers protested in South-Central Los Angeles, and the Board of Supervisors voted to raise more than $9 million in taxes in unincorporated areas and some cities--money that will be used to save services at county libraries.

Besides the palpable sense of gloom and dismay that pervaded the county Hall of Administration and offices countywide Thursday, the specter of mass layoff notices suddenly made the health crisis seem more immediate to all involved.