"They are attempting to get it extinguished," he said.
Water-supply problems and concern about firefighters' safety due to the thousands of solar power units on the roof reportedly hampered fire-quelling efforts.
Delanco Fire Chief Ron Holt told NBC-10 his men had to hold back at times because of the danger of electric shock from the charged panels.
"With all that power and energy up there, I can't jeopardize a guys's life for that," he said. Holt and Township Administrator Richard Schwab, who is also the public safety director, did not return calls Tuesday.
Ken Willette, a manager with the National Fire Protection Association, said studies had established the risk of electric shock to firefighters from solar panels as well as the challenge they can present to fire-scene access.
But, he said, while firefighters are aware of these issues, there is no national protocol for placement of panels with regard to firefighting access and safety.
"It's still being done on a state-by-state and locality-by-locality basis," Willette said.
Installers of the solar power units may be focusing on energy-cost savings, not firefighting, he said.
Willette said that from the information he had received, there would have been no easy way to turn off the power on such a large area with so many units.
Only a few firefighters sustained minor injuries, included Holt, who injured his ankle, DeSanto said.
The warehouse was closed when the fire broke out, so no employees were hurt.
Earlier Tuesday, residents near the warehouse, especially those with respiratory problems, were advised by officials to stay inside. Later in the day, DeSanto said air quality was determined to pose no hazard.
Dietz & Watson opened the Delanco site in 2007. Riley said the company's Philadelphia facility would need to assume a major role in distribution.
The company also has a distribution center in Greenville, S.C., and a plant in Baltimore that can handle some of the distribution.
In Web messages, Dietz & Watson expressed appreciation of first responders' efforts and customer and community support.
"We're a family company, and we will come out of this stronger and closer than ever," read a statement on the company Facebook page.
Contact Rita Giordano at 856-779-3893, email@example.com, or on Twitter @ritagiordano.