LOUDOUN COUNTY, Va. (WRIC) — Firefighters rescued one unconscious occupant from a house fire — costing an estimated $351,000 in damages — in Loudoun County earlier this week.

Shortly before 4 a.m. on Monday, Feb. 6, crews with the Loudoun County Fire and Rescue were called to Thrush Road in Sterling for a reported house fire. According to authorities, a passerby had called in the fire after seeing smoke coming from the building.

Upon their arrival, firefighters found the fire coming from the rear of the home and immediately made entry. Crews managed to rescue one unconscious adult and several unresponsive pets.

The adult occupant was transported to Inova Lansdowne Hospital and remains in critical condition, according to authorities. Loudon County Animal Services arrived to assist two dogs and one cat but they did not survive.

An investigation by the Loudoun County Fire Marshal’s Office determined that the house fire was accidental and had been caused by a malfunctioning lithium-ion battery pack. The damages to the home and its contents cost an estimated $351,000. According to authorities, the home was found to be without working smoke alarms.

Other fire rescue units from Cascades, Kincora, Sterling Park and Fairfax County assisted with the incident.

Following the incident, Loudoun County Fire and Rescue has shared a number of tips for house fire prevention which can be found at their website.