Friends, neighbors and community members are in mourning after two men were killed inside a Bensonhurst apartment Monday night.

Officials say they believe the cause was a carbon monoxide leak.

Police say two men, a 49-year-old and a 50-year-old, died Monday night at 170 Avenue O.

Inspectors with the city's Department of Buildings tell News 12 there was a carbon monoxide leak in the cellar of the building.

Both men were pronounced dead at the scene.

The DOB's preliminary investigation found that the building was illegally converted with the addition of illegal single room occupancy units, that the boiler chimney was blocked off with debris and there was also evidence of gas back up and unpermitted electrical wiring.

The DOB has issued a full vacate order, and the American Red Cross is providing housing and other support for 10 people who have been affected.

In an effort to get the word out about how families can prevent a similar incident from occurring, the FDNY Fire Safety Education Unit took to the streets on Tuesday to give out free smoke and carbon monoxide detectors and provide other useful information.

The identities of the two men have not yet been released. The investigation into this incident is on-going.