An eight-year-old girl is in a critical condition after being shot by her adult cousin who mistook her black and white Halloween costume for a skunk.

Janet Grant, who was hosting a Halloween party on Saturday night, shone a light for her son Thomas, 24, to help him shoot what they thought was the animal, but, to their horror, turned out to be the little girl, police said.

The girl was hit in the shoulder, arm, back and neck in the shooting in Rochester, a rural area about 30 miles north west of Pittsburgh, Pennsylvania, where firearms and hunting are common.

Ms Grant said someone had told her at around 8.30pm that there was a skunk nearby and she asked her son to shoot it, New Sewickley Township police chief Ronald Leindecker said, according to the Beaver County Times.

Thomas Grant grabbed a shotgun while his mother pointed the beam of a flashlight at a nearby hillside, Chief Leindecker said. Mr Grant spotted what he thought was a skunk under a tree and fired, but then he heard a scream from his cousin.

The girl was wearing a black body costume and a black hat with a white tassel.

People who live in the quiet country neighbourhood said neither Mr Grant nor his family had ever caused problems.

"Nobody can really understand it," said Dan Reese, who lives next door to the house where Mr Grant fired the shotgun. But he said Mr Grant should not have been shooting at that time of night or near other houses.

The Grant house sits off the side of a small hill and at least two other houses appear to be within 100 yards. That could be important because it breaks state hunting rules to shoot a firearm within a 150-yard safety zone around another occupied residence.

State officials also say that while it is legal to hunt skunks and to hunt them at night, that requires what is known as a furtaker licence. It's unknown if Mr Grant had one.

Chief Leindecker said a "thorough investigation" was under way and no charges had been filed. No-one answered the door of the Grant house last night.

Investigators have not named the girl, who was flown to Children's Hospital of Pittsburgh. A spokeswoman there declined to comment on her condition.

Mr Reese said the girl may have been lucky because local nurses apparently were with her when she was shot.

Belfast Telegraph