HOUSTON -- A teenager has confessed to starting a fatal three-alarm fire at a northeast Harris County apartment complex, officials told KPRC Local 2.

Family members consoled one another after learning their sister, Linnafaye Skinner, was trapped inside her unit of the Timber Run Apartments in the 13000 block of Woodforest Boulevard near Rivergrove Drive as it burned.

Relatives said she was diabetic, semi-blind, and could not move very well. Investigators found her remains several hours after the fire started at about 11 p.m. Sunday.

Terra Crooms, the victim's sister said, "She was our hero because she called 911 and she saved everyone here."

The fire destroyed dozens of units, almost all of which were occupied.

Arson investigators arrested 19-year-old Joshua Mims. Detectives said he confessed to breaking a window in apartment 13 and setting the fire in there out of retaliation.

Investigators said Skinner's apartment was next door to the unit where the fire was set.

Several fire departments helped put out the fire that engulfed buildings 12 and 13.

A woman who lives in another building said she remembers people fighting right before the two buildings caught fire.

Sylvia Carrizal said, "It was engulfed when I was walking through there. It was all engulfed in there, especially where the fire started."

Mims faces felony arson charges.

Arson investigators have not said exactly how Mims started the fire.