TROY— The July 19 fire that tore through the Marshall Ray building at 701 River St. was caused by "spontaneous heating of discarded construction materials," according to a fire investigation report released Tuesday by the Troy Fire Department.

Two city firefighters were injured while fighting last Friday's blaze, but both received treatment and the injuries were considered non-life threatening, according to the department's report.

Redburn Development had undertaken a $16 million renovation of the former factory building to develop 77 mostly one- and two-bedroom units. Construction on the building began last fall.

The report concluded the fire originated in a garbage can on the southwestern side of the building's fourth floor. Fire officials believe the trash can had a pile of sawdust, metal shavings, sanding disks, empty bottles and other debris. A number of cans of polyurethane were found immediately near the trash can.

The spot on the fourth floor where the fire started was a staging area for construction material being used on that floor. Hardwood flooring had been stockpiled, as well as fiberglass and plastic plumbing fixtures and quarts of polyurethane, according to the report.

Cardboard boxes had also been discarded on the fourth floor nearby.

"As the fire grew beyond the garbage can of origin, these items became involved and as a fuel package provided a prime fuel source for the rapid growth, development and spread of the fire," the report read.

Firefighters battled the fire for hours, going "late into the night," according to the fire department's report.

Fire suppression and detection systems were under construction in the building at the time of the fire, but were not yet operational.

The future of the apartment project is unclear, but workers have been seen recently working to repair damage to the building.

The fire's was focused in the top three floors of the building. The bottom three floors primarily suffered water damage, and other minor damage from the fire.

A Troy city official has said the project will continue, but attempts to contact Redburn this week have been unsuccessful.

The project, which was also set to include 15,000 square feet of retail space, was awarded a $1.8 million grant from the Restore New York Communities Initiative. It also received $3.68 million in tax breaks from the Troy Industrial Development Agency.

Visitors to the website for the apartment development — dubbed the "Collar Factory Lofts" — on Tuesday saw a new notice on the site.

"On Friday, July 19th, our wonderful building suffered tremendous damage from a terrible fire," the post read, referring to the building at 701 River Street. "We pride ourselves in figuring out things that seem impossible. Today, impossible means we may be starting over...For now, we just have a different puzzle to solve. When we figure that out, we will be sure to let everyone know."