ALLENTOWN, Pa. — Allentown firefighters are battling a massive fire Wednesday night at a former industrial building near the city’s riverfront.

Emergency radio dispatches indicated the fire had escalated to a sixth alarm shortly before 10 p.m., less than 90 minutes after it was first reported.

The blaze was reported at 8:41 p.m. on North Front Street near Gordon Street and Riverside Drive and spread rapidly. Thick black smoke poured from the building and was visible from miles away.

The Allentown Fire Department urged residents in the surrounding area to shelter in place because of the heavy smoke. Radio dispatches also indicated some nearby residents were being evacuated.

Residents on the 300 block of Front Street were asked to immediately leave their properties through their backyards, according to the fire department.

According to the PPL Electric Utilities website, nearly 3,500 customers were without power due to the blaze.

Allentown City Councilwoman Ce-Ce Gerlach said on Facebook anyone affected by the fire can go to Resurrected Life (the old Liberty Bell Church) at 620 W Hamilton St for refuge.

The American Red Cross also was responding, dispatches said.

This story will be updated.