Shannen Doherty Calls Cops -- After Twitter Fan Threatens Suicide

Shannen Doherty went above and beyond the call of duty to help a possibly suicidal fan Sunday night ... working with police from across the country to make sure the fan didn't harm herself ... TMZ has learned.

The Westampton Township Police Department in New Jersey confirms ... Doherty -- who lives in L.A. -- contacted officers late Sunday night and told police she had been receiving several disturbing tweets from a fan who threatened to kill herself unless she got a phone call from the actress.

Sources close to Shannen tell TMZ ... the actress had reason to believe the fan was in possession of a gun.

According to the WTPD, Shannen was able to get the fan to reveal her address ... and cops were immediately dispatched to the woman's home.

Once police arrived, the officers met with family members who said the person of interest was a 27-year-old woman who was at home in her room.

Cops spoke with the woman ... who insisted she did not wish to harm herself. Cops also say they found nothing that would lead them to believe she was a danger to herself.

The woman was offered medical attention -- which she declined -- and cops left the scene after determining she was safe in the care of her family.