CONROE, Texas (AP) — Authorities say a house fire north of Houston has killed two brothers and their sister and injured another brother, their grandparents and an uncle.

The fire broke out around 4 a.m. Friday near Conroe (KAHN'-roh). Investigators say police tried to reach the second floor to rescue children but were driven back as flames engulfed the home.

The Montgomery County Fire Marshal's Office said the children who died were 13-year-old Terrance "TJ" Mitchell, 6-year-old Kaila Mitchell and 5-year-old Kyle Mitchell.

Their 10-year-old brother was rescued but injured. His condition hasn't been released.

Memorial Hermann Hospital in Houston says the children's grandfather and uncle are in serious condition, while their grandmother is in good condition. All suffered smoke inhalation and burns.

Three police officers also suffered smoke inhalation and lacerations.