Firefighters battling a large truck fire near Springfield and Dietrich roads off W.W. White discovered a body in the backseat early Thursday morning.
A security guard noticed the truck fire on the East Side around 1 a.m. and called the fire department.
Firefighters put out the blaze and found what is believed to be the body of a man inside the extended cab pickup.
San Antonio police homicide detectives were called to the scene to investigate, but said there were few clues about who the person was or what happened.
Detectives were also unsure whether the victim died in the fire or before the truck burned.
SAPD detectives suspect the fire was intentionally set because the cab of the truck was badly burned, but the bed didn't catch fire.
The fire department's arson unit is investigating the fire as well. The body has not been identified.

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