"There was very little smoke coming out," Troy Gleason said. "I tried to run around back, but I couldn't get around to see, and (Kathryn) was calling 911."
The Post-Star will be providing video coverage of the fire in the morning.
The business, established in 1946, provides customers with home and auto glass, storefront windows, tub enclosures and decorative glass items, such as mirrors and table tops. It is owned by Jim DelSignore and Jim Mazza, both of whom arrived at the fire shortly after firefighters forced entry to the building and began work to save it.
"Not a clue," DelSignore said when asked if he knew what could have caused the fire. "We keep a couple of vehicles on this side," he added, motioning to a garage addition to the building. "It could be electrical, I don't know."
Neither DelSignore nor his partner, Mazza, were at the business when it closed at 5 p.m., they said.
"We've got two gentlemen who close up for us," Mazza said.
Adirondack Glass has been a family-run business since it opened under ownership of Earl Strader Sr. and Earl Strader Jr. in October of 1946, according to a history of the company published by The Post-Star in a 1996 article.
"We're 59 years almost to the day," Mazza said as he watched firemen work on the building Monday.
Jim DelSignore's father, Frank DelSignore, joined the Straders in the firm in the early 1950s and established the company's insurance auto glass replacement program. Mazza is the son-in-law of Earl Strader Jr.