PHOENIX -- Authorities warned pet owners in the east Valley Monday that someone is intentionally injuring and killing cats.

At least 14 cats have been found with long, deep stab wounds across their backs, according to the Maricopa County Sheriff's Office Animal Crimes Division.

Two of the felines have died as a result of the injuries. The others required costly veterinarian care.

Sheriff Joe Arpaio said investigators need help finding those responsible.

“At this point in our investigation, we have no leads and no suspects,” Arpaio said, “but someone out there knows who is doing this and we need that person to contact us with the information."

He said he has ordered the volunteer posse to help assist deputies in the investigation.

The Humane Society of the United States is assisting the sheriff’s office by offering a $2,500 reward leading to the arrest of the attacker.

“Keep your cats indoors,” Arpaio warned. “There is a sick person on the loose right now looking to harm them.”

People with information can call the sheriff’s animal abuse hotline at 602-876-1681.