San Marcos Police have arrested three suspects in an arson spree that spans two cities.

San Antonio firefighters arrived early Friday morning at an Aamco Transmission store and were greeted by flames shooting through the roof.

There wasn't much they could do to save the business, so they worked to keep the flames from spreading.

Less then 30 minutes later, another fire broke out in San Marcos.

A police officer driving down Highway 123 at 1:45 a.m. noticed something unusual at the transmission shop.  She heard an explosion. She also saw flames and three people running from the scene, including one whose clothes were on fire. She held all three until other officers arrived on scene.

“The building basically exploded and burned and three subjects were taken into custody,” said Fire Marshal Kenneth Bell.

Bell and others spent Friday looking through the charred remains for clues.

“As you can imagine we're real deep into the process.  It's very methodical we use a scientific method in this process where the fire originated and how it originated,” said Bell.

Manny Gomez works at the San Marcos location.  A friend called to tell him the shop was on fire.

“It was shocking I didn't expect this one to be burned down too the other one I was watching on the news,” said Gomez.

The arson suspects are Adam Rodriguez, age 26; Michael Rodriguez, age 18; and Jeremy Garcia, age 19. They all come from San Antonio.