Jan 10, 2013 9:40 PM CST

HALTOM CITY, Texas - Three children and an adult woman were killed in a house fire in Haltom City Thursday evening.

Fort Worth fire officials said a neighbor called 911 after he saw smoke coming out of a second-story window of a house in the 4900 block of Colonial Park Drive.

He didn't think anyone was inside, but when firefighters arrived they found four people suffering from smoke inhalation.

All four were rushed to area hospitals, but Medstar officials said they did not make it.

They were described as a 6-month-old baby girl, a 5 to 6-year-old boy, a 10 to 11-year-old girl and an adult woman.

Firefighters still don't know how long the victims were in the home breathing in the smoke before being rescued.

Officials have not yet determined what caused the fire. Arson investigators were called to the scene.