"All companies [will be] operating for some time," the Stamford Fire Department said via Twitter @SFDPIO.
The fire was first reported on Alden Street at about 5:30 pm. Monday, the fire department said.
"Second Alarm - 46 Alden Street, all companies working," Stamford Fire said minutes later.
"All companies working for extended time, multiple units operating at the scene. 2 houses involved," Stamford Fire said via Twitter.
At about 7:15 p.m., the Stamford Fire Department said via Twitter that the inferno had grown into a five-alarm fire.
Firefighters said the neighborhood where the huge blaze broke out is very densely populated, with houses close together. It is presenting "significant challenges for firefighters," the department said via Twitter.
NBC Connecticut has aerial shots of the fire on its Facebook showing flames shooting from the roof of one house and smoke engulfing the area around Stamford Hospital.
No further information was immediately available on the fire.
Click here for an aerial video of the fire at the NBC Connecticut Facebook page.
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