Two young girls were treated for carbon monoxide poisoning yesterday after they collapsed inside their mother's idling car. Their mother had put the 4-year-old and 7-year-old in the car outside of their home on West Tremont Avenue to stay warm while she shoveled the driveway. However, the mother "accidentally shoveled snow in front of the running vehicle's tailpipe - blocking the opening and sending noxious fumes back inside," arrived within two minutes and performed CPR on the girls, who were taken to Jacobi Medical Center. They were treated in a hyperbaric chamber and returned home in the evening. Police believe the incident was an accident. Neighbors told the Daily News, "She's a good mother," and "The kids, I think they were a distraction [when they were playing outside while the mother shoveled]... So she put them into the car and a few moments later, she saw them unconscious in the back seat."