The fire was so intense, it blistered the paint and melted the light bar on the fire truck.
Two houses, at 2310 and 2312 West 23rd Street, went up like tinder wood.
And the three fire hydrants nearby had apparently been tampered with, possibly by the arsonist.
"To the extent that two pretty good size guys were jumping on them--400 pounds of guys jumping on them--and they couldn't budge them," said Mike Wallace of the Neffs Fire Department. "They bent wrenches in half. It became a problem and it may have been by design."
Flames could be seen from across town as the two houses were engulfed.
Fire officials say the two old structures were supposedly unoccupied, but there is some question about that.
One of the two houses was built down over the hillside, and the fire in the lower levels is still being fought today.
"These particular ones have a couple sub-basements so you're looking at the property of almost a five-story building," said Wallace.
An investigator from the state fire marshal's office is on the scene.
And firefighters have a message for the arsonist.
"Well, you can run but you can't hide," warned Wallace.