A Toms River house fire that left two people critically injured this weekend was caused by “careless smoking while oxygen was in use,” Ocean County Prosecutor Bradley D. Billhimer announced Tuesday. The fire broke out shortly after 9:30 p.m. on Sunday at a home on Mount Everest Lane and during a search, firefighters discovered two 73-year-old people inside, according to a statement from the prosecutor’s office. They were flown to the Burn Center at Cooperman Barnabas Medical Center in Livingston for treatment, authorities said. One of the residents, a man, remained in critical condition Tuesda…