Paris Hilton has some intense fans -- but last night, one hopped the express crazy train with her loco reaction to seeing the heiress.

TMZ caught Miss P and Sexy Lexy leaving Villa late last night, when a fan went berserk for Hilton -- screaming at the top of her lungs, practically weeping to get attention.

Paris screamed "I love you too!" toward the wacky admirer, though the fan probably didn't even hear it -- due to her own insane screaming.