The Los Angeles Police Department responded to a call from the 5400 block of Hollywood Boulevard around 3 p.m. Monday.
LAPD was told the woman tried to attack the security guard with a fire extinguisher. She was also believed to be armed with a screwdriver, LAPD said.
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The woman was taken to the hospital where she was later pronounced dead.
Officials did not say what prompted the woman to target the security guard.