PHOENIX -- Investigators are looking into a suspicious fire that started early Friday morning inside a closed and locked executive office building near Metrocenter.
It happened at about 12:30 a.m. at 31st and Peoria avenues, which is adjacent to the mall.
More than 50 firefighters from Phoenix and Glendale responded.
The first floor of Metro Executive Park's south building houses a realty company. The second floor is unoccupied. That's one of the reasons firefighters labeled the fire suspicious.
They said it looks like the fire started in an elevator shaft on that vacant second floor. It is not clear what sparked it.
Flames burned through some insulation releasing toxic fumes.
Crews knocked down the fire quickly and contained most of the damage to the roof.
No injuries were reported.