Police in the eastern Ontario town of Rockland say they shot and killed a pit bull last week after they say it attacked a woman and her 10-year-old son.

Ontario Provincial Police say at about 8:20 p.m. Friday a person on Laviolette Street in Rockland called police after the boy left the neighbouring house screaming that he had been bitten by the dog and that the dog was attacking his mother.

Police entered the home where they found the 34-year-old woman on the ground and the dog on top of her.

The officers tried repeatedly to get the dog off the woman, but each time they did, the dog attempted to attack the woman again, according to Const. Serge Gauthier with the Russell County OPP.

Gauthier said police were forced to shoot the dog.

The woman and her son were dog-sitting when something set the dog off, Gauthier said.

Gauthier did not know the exact breed, but described the dog as a pit bull.

Both the young boy and the woman were bitten in the legs and were transported to hospital with serious injuries before they were released. The woman needed around 30 stitches, said Gauthier.

It's not known if the owner of the dog has been contacted, but police said they did not expect charges to be laid. Police expect to file a report, however, on the discharge of the weapon.

The Eastern Ontario Health Unit is investigating whether or not the dog had rabies or previous behavioural or medical issues.