Three men died and a fourth was hospitalized in Northern California after what authorities believe were fentanyl overdoses.

Santa Clara County sheriff's deputies were called to a home in an unincorporated area near Gilroy just after 3 p.m. Monday to help firefighters, the Sheriff's Office said.

Deputies found the men, all in their 50s, unresponsive and gave them Narcan, the office said.

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Naloxone, known by the brand name Narcan, is used in emergencies to reverse opioid overdoses.

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Three men in Northern California died of a suspected fentanyl overdose. (Fox News)

Three of the men were pronounced dead at the scene. The fourth was hospitalized but there was no immediate word on his condition.

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The names of the victims weren't immediately released.

The four are believed to have overdosed on fentanyl, authorities said, although the Medical Examiner-Coroner’s Office will determine the official cause of death.

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Fentanyl is a synthetic opioid 80 to 100 times more powerful than morphine. It has been blamed for thousands of deaths in California alone.