Authorities have confirmed a fourth death from a fire that broke out at a San Antonio group home for the mentally disabled Wednesday night.

The fourth victim, Jesse Brooks (23) had been in critical condition following the fire and died from his injuries Thursday. The other three victims are Eddie Lee (65), William Stull (42), and Christopher Breeze (38).

There were 13 mentally challenged men living in the house. Arson investigators believe the source of the fire started in one of the residents closets, but are waiting on witness accounts of the incident to confirm it.

"It's very difficult to get interviews, and we're calling in a specialist from San Antonio Police that's going to help our arson investigators do interviews with people that are mentally challenged. So that is a challenge for us because these are our witnesses," said San Antonio Fire Chief Charles Hood.

Fire Officials say a neighbor called 911 late Wednesday night to report the blaze.

By: Marissa A. Wagner and Bill O'Neil