The man's sister reportedly called police around 6 p.m. Monday and said her brother was trashing the house, though she was not there at the time, according to MySA.com.
When officers arrived at the scene in the 7500 block of Dream Valley near Millers Pond Park, they found a man and woman in their 60s with gunshot wounds. The victims had reportedly been dragged onto the front yard by neighbors since the home was on fire. Both were pronounced dead at the scene.
Once firefighters diminished the blaze, SWAT officials entered the home. They found both the suspect, who has yet to be identified, and his 80-year-old grandmother dead, San Antonio Fire Chief Charles Hood said.
The grandmother's cause of death isn't yet known, but Hood said she likely wouldn't have survived due to the smoke inside the home. The fire department is now investigating how the fire started.
Police chief William McManus believes the three victims all lived at the home. Officials will now investigate a motive and cause of death for the victims and suspect, but it is assumed to be a triple murder-suicide.
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