It took 24 hours and an estimated six million gallons of water for area firefighters to extinguish Monday’s deep-seated fire in the scrap pile at Penn Recycling on Trenton Avenue, according to city fire officials.

The fire in the four-story high scrap pile that was the size of football field broke out about 2:20 p.m. and firefighter remained on the scene until the middle of the following afternoon when the last smoldering embers were put out.

Firefighting crews were rotated on and off the scene during the fire. The cause of the blaze remains undetermined. City firefighters were assisted by several volunteer fire companies.