By Oren Liebermann

HORSHAM, Pa. (CBS) – An apartment complex was evacuated Sunday afternoon after flames tore through an office building in Horsham, Montgomery County.

Firefighters were called to the 200 block of Blair Mill Road just before 2 p.m.

Investigators are still trying to determine exactly what caused the fire. They know it started as a mulch fire, but aren’t sure what sparked that mulch.

By the time the fire was out at the Blair Mill Professional Center, the two-story office building was destroyed.

Investigators say the flames started as a mulch fire in front of the building, then spread quickly, first to some shrubs, then to the building itself, pushed by high winds.

Investigators say two people were inside at the time, but both got out safely before the fire gutted every office. No injuries were reported.

“Everything was confined to that building, however, it is substantial and the damage is — there’s four tenants currently that are occupying that building, there’s three tenants based vacancies and clearly they’re out of there. It’s substantial,” Horsham Township Fire Marshall George Fida said.

High winds pushed heavy smoke towards nearby apartment buildings, forcing firefighters to evacuate the apartments for safety.

“First arriving firefighters had to fight the wind which really grabbed hold of that mulch fire and started spreading quickly, Fida said. “If it wasn’t so windy maybe we would have had a shot at this.

Fire officials say all the neighbors who were evacuated have been allowed back inside. There was no damage to any of those apartment buildings. All of it was focused right on that office building that has been destroyed.

“I couldn’t believe how it ripped through the building and how many engines came to put this out,” neighbor Eddie Goldstein said.

Investigators say it doesn’t appear this fire was suspicious, but they are still looking into the start of that mulch fire.

Top Content On CBSPhilly

Watch & Listen LIVE