The fire that completely gutted the historic Masonic Temple, Monday, has been ruled accidental, according to an AP report.

Investigators determined the fire started when workers accidentally ignited insulation, according to a spokeswoman with the state Department of Fire Services.

The Masonic Temple on Hancock street is ablaze, according to CBS.

Crews are on site, battling the the four-alarm fire that reportedly started around noon time at 1170 Hancock St.

[UPDATE 1:47 p.m.] Boston.com reports that firefighters were ordered out of the building around 1 p.m. and continued to attack the blaze from the outside.

[UPDATE 3:59 p.m.] Quincy police told Boston.com that Police have closed Hancock Street in Quincy from Washington Street and Granite Street northbound to Furnance Brook Parkway. A section of Newport Avenue and Adams Street in Quincy were also closed, as well as the Quincy Center T stop on the Red Line.

[UPDATE 4:02 p.m.] Channel 7 reports that authorities do not believe the fire was set intentionally. Firefighters are expected to remain at the scene throughout the night.

The fire may have started in the basement of the Masonic Temple before spreading through the ductwork, Boston.com reports.

The plume of smoke from the roof was reportedly picked up by the National Weather Service radar, according to Boston.com.

A jewelry store owner told CBS Boston that ash filled the air as soon the the roof of the building became “fully engulfed.”

WCVB.com reports that workers inside the building said smoke was coming from the air ducts.

Twitter pic from @JessBarton11

The historic building was built in 1926. According to the Patriot Ledger, the building was put on the market for sale in July for $3 million.

No injuries have been reported and the cause of the blaze remains unknown.

WCVB reports that authorities have secured a two-block radius around the structure. As of now, nearby apartments have not been evacuated.

This story is developing.

You can read more stories on Boston startups, technology and innovation at https://www.bizjournals.com/boston/inno