December 14, 2010 2:30 PM

By SCOTT T. SMITH / WPEC-CBS12.com

PORT ST. LUCIE, Fla. — A Port St. Lucie jogger used his bare hands to kill a large black Lab-chow mix that attacked him and his 7-year-old son on Southwest Masilunas Street Saturday.

Port St. Lucie police say they interviewed the victim, 32-year-old Josh A. Harris, shortly after the attack and reported him bleeding heavily from the nose with numerous bites and scratches on his face and arms.

The man told police his son was riding his bike in front of him when they approached a home in the 3600 block of SW Masilunas St. Saturday morning. Harris said he was southbound when they noticed the large dog staring at them from the front yard of 3633 SW Masilunas. Harris told his son to get behind him and the now barking dog charged them as they passed the house, lunging and jumping on Harris.

Harris told police he was able to get the dog on the ground after a struggle and held it by its neck to stop it from biting. Police say it’s not clear if he choked it to death or broke its neck, but it was dead by the time help arrived.

The dog’s owner, Peggy Hamilton, 59, said she was unaware the 5-year-old Lab-chow mix named Sierra, which weighs about 85-100 pounds, was running free. She said all of the dog’s shots are current, but she wasn’t sure about rabies. The dog will be tested for the deadly virus.

Harris’s son, Jackson, had banged on a neighbor’s door during the attack. Getting no response, his dad told him to ride his bike home and get his mom. The two returned to the scene and police interviewed him.

Hamilton said the dog had never acted this way before.

Police described Harris’s injuries as serious and he was taken to the emergency room at Martin Memorial Medicenter for treatment. His latest condition wasn’t immediately available.