A fire on Manhattan's Upper West Side forced residents out into the cold Tuesday morning. The FDNY said at least two people were taken to the hospital to be treated for injuries.

The fire started around 8:20 a.m. Tuesday on the top floor of a six-story building on West 107th Street near Amsterdam Avenue. 

At this point, it's unclear how many units are in the building, or how many people may have been forced to evacuate.

The city's Office of Emergency Management says it is working with the MTA to bring in warming buses. Temperatures are currently in the 20s, making it a cold morning for residents and first responders.

Watch Chopper 2 over UWS fire

Chopper 2 flew over the building, where thick smoke could be seen billowing into the sky. The flames appeared to have burned through a portion of the roof. 

The FDNY shared a photo of the damage on social media, showing a section of the sixth floor collapsed, as well. 

Firefighters could be seen battling the blaze from atop the roof and from ladder trucks below. 

The fire prompted a four-alarm response, with approximately 140 fire and EMS personnel on the scene. 

Nearby streets are closed as the firefighting efforts continue. 

Check back soon for the latest updates on this developing story.