NATRONA HEIGHTS, Allegheny County — A number of Butler County fire departments assisted Monday night in fighting an intense blaze that destroyed a dozen businesses in a strip mall here.

Fire crews were expected to wait for daylight this morning to resume searching for the cause of the fire, which engulfed much of the Heights Plaza in Harrison Township about 9:40 p.m.

Customers at J&S Pizza first saw the flames in the restaurant’s facade, but fire officials say it spread quickly to other businesses.

“We think it started in the pizza shop, then it just spread through the roofs across the mall. It was pretty bad,” said Chief Chris Ballina of the Saxonburg Volunteer Fire Company.

Ballina said 15 Saxonburg firefighters responded to the blaze, using the department’s ladder and tanker trucks and two engines.

Chief Bill George of the Sarver Volunteer Fire Company said about 11 of the department’s firefighters assisted with a ladder truck and an engine.

“It was pretty well knocked down when we got there. We had to go through the roof of one building and were doing mostly overhaul,” George said, referring to the process of searching walls and ceilings for hot spots or small fires that remain unextinguished.

According to the Butler County Emergency Services website, the Herman, Adams Area, Middlesex, Buffalo Township, and Penn Township volunteer fire departments in Butler County also responded to the blaze or were available on standby.

The fire likely caused millions of dollars in damage and has closed businesses that employ dozens of people just a week before Christmas.

No customers were hurt.

Harrison Township is along the Allegheny River about three or four miles south of Freeport.