Residents of a San Francisco Bay Area city are on the lookout for an aggressive squirrel that has sent at least two people to the emergency room for medical treatment.

Joan Heblack told ABC affiliate KGO-TV that she was walking in the Lucas Valley neighborhood of San Rafael when a squirrel seemingly came out of nowhere and attacked her leg, clawing and biting.

“It clamped onto my leg. The tail was flying up here. I was like: ‘Get it off me, get off me!’” Heblack said.

Isabel Campoy also said she was attacked while walking in the same area. The squirrel launched itself from the ground to her face and wound up on her arm, leaving it bloody, she said.

Both women went to the emergency room, the TV station reported in its Monday story.

Flyers have now been posted, warning residents that the squirrel is no joke and that more than five people have been attacked by a “very mean squirrel” that “comes out of nowhere”.

Vanessa Potter of WildCare, a wildlife rescue organization in San Rafael, told KGO-TV that the aggressive behavior likely comes from the squirrel being fed and cared for by humans when it was a baby.

She said squirrels are not vectors for rabies. Experts say the public should not feed wild animals.

The city manager’s office did not immediately return a phone call seeking comment. San Rafael is in Marin county, about 20 miles (32km) north of San Francisco.