LOWER MERION, PA — A powerful underground fire pushed high levels of carbon monoxide into a Wynnewood shopping center overnight, officials said.

The fire, reported at 10:51 p.m. Tuesday, brought heavy flames and smoke to the back alley of Wynnewood Square — a strip mall on East Lancaster Avenue, anchored by Target.

Firefighters battled the blaze and made sure all stores were evacuated while checking for smoke.

The smoke and fire were controlled in four hours, according to the Merion Fire Company of Ardmore.

High levels of carbon monoxide were found in several stores, officials said. Specific businesses weren’t specified, but photos from the scene showed firefighters outside of Petco and Five Below.

Firefighters turned over the scene to PECO and the Lower Merion Fire Department’s Fire Marshal’s Office.

This is a developing story. Check back for updates.