Authorities are investigating the cause of a Monday night fire that claimed the lives of two men and critically injured another, according to police.

At about 10:28 p.m. police responded to a 911 call of a residential fire inside a home at 42-24 Ithaca St. in Elmhurst, the NYPD said.

According to PIX11 New York, the fire at the two-story house grew to a second-alarm fire and spread to the residence next door. The fire was under control by midnight. 

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Once FDNY personnel extinguished the fire, responding officers discovered three men, unresponsive and unconscious, within the home, according to police.

Emergency personnel took two of the men to Elmhurst General Hospital, where one of the men was pronounced dead and the other is currently listed in critical condition, cops said. The third man was take to Forest Hills Hospital where he was later pronounced dead.

The identities of the men have not yet been released pending family notification.

According to PIX11, a firefighter was also hospitalized but has since been treated and released.

The city’s Fire Marshall will determine the cause of the fire and investigators at the medical examiner's office will determine the cause of death for the two men.