Gilbert, Ariz. -- Fire investigators believe an improperly discarded cigarette is to blame for a multi-million dollar blaze at a business in Gilbert on Monday.
The Farnsworth Plumbing Supply Company went up in flames that could be seen Valley-wide.
Emergency crews said it was the biggest fire they have seen in Gilbert in at least a decade.
It took them hours to get the fire under control, and once it was, investigators began figuring out what happened.
They reviewed witness statements, video, and the fire patterns.
Gilbert fire investigator, Josh Friedman, told 3TV that an employee improperly discarded a cigarette, sparking the blaze.
"It's an accidental fire, so there are no charges," said Friedman.
The damage is estimated at more than $8 million.
Employees of nearby businesses reported hearing the explosions and feeling vibrations.
"We started walking over here and then next thing you know it was just pluming smoke," said Aaron Hagen, the owner of the Cactus Valley Pool Supply. The businesses are next to each other.
Jack Stapley, a co-owner of Farnsworth Plumbing Supply Company said a warehouse was destroyed and an office building facility was also badly damaged.
The business has been in Gilbert near McQueen and Baseline roads for 18 years.
The fire started shortly after 3 p.m. Monday and burned intensely for nearly three hours.