Delanco Fire Chief Ron Holt said crews were on "fire watch" at the Coopertown Road building overnight Wednesday until 7:30 Thursday morning.
Some "lingering hot spots" remain, buried under collapsed roof panels, but firefighters can't get to them until more demolition work is completed, Holt explained. "We can't do anything until areas that are not safe are knocked down."
He said Dietz & Watson is handling the demolition of what remains of the building, which will expedite the ongoing investigation into the cause of the fire.
Investigators from the New Jersey and Burlington County fire marshal's offices are involved in the investigation, as well as the Delanco fire marshal and agents with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).
Holt said ATF was primarily involved to rule out that the fire was caused by arson, which investigators have done. He was unsure how long the investigation would last, but speculated it could take up to a week or two.
Sunday's 11-alarm blaze was the biggest fire Holt has been involved with in his 35 years as a firefighter, 15 of those with Delanco. The next largest fire he could recall was the DistribuTech warehouse fire in 1998, which went to five alarms.
Wednesday night was the first full night's sleep Holt has gotten since the blaze broke out just after 1 p.m. Sunday. At the height of the firefighting efforts, the chief was up for 30 hours straight.
That tireless work ethic may have contributed to a nasty spill that left Holt with a broken ankle. He said he was doing a "walkaround" of the warehouse when he stepped off a path near the building onto an uneven patch of ground and fell.
Despite the discomfort, Holt stayed on the scene.
"Being the chief of the company, I wasn't about to leave," he said, explaining how he slapped some ice on it, wrapped it, and went about his duties.
Holt was one of five firefighters who sustained minor injuries—his broken ankle being the worst.
More than 300 firefighters from dozens of local companies helped battle the blaze.
"I can't even put into words the gratitude I have for all the companies that responded," Holt said. "It's the perfect example of ICS (incident command system)—the way it's supposed to work."
Dietz & Watson also expressed its deep gratitude to the first responders in a statement on its website. Company spokesman Steve Riley said every one of the 100-plus jobs at the Delanco warehouse are safe. The employees are currently working out of the company's Philadelphia facility.
The Burlington County Health Department advises residents if they have any questions or concerns in reference to a health issue related to the warehouse fire, they can contact the Health Department at 609-265-5515.