BUFFALO, N.Y. -- Two firefighters were injured and two homes were destroyed after a massive fire broke out in Buffalo's Black Rock neighborhood Monday morning.

The fire started just before 6 a.m. in a vacant house under construction on Grote Street, which then collapsed.

Flames soon spread to a building on Military Road. Five people from that structure, including one child, were able to get out safely. A third house on Grote was also affected.

One firefighter hurt his shoulder and another is dealing with a respiratory issue -- both were taken to the hospital.

Slick roads slowed firefighters down on their way to the scene.

"Crews getting here, seeing that fire there, not knowing if that building there was occupied, and then impinging upon the other building. So, it was a hectic scene upon their arrival," said Buffalo Fire Commissioner Garnell Whitfield.

Fire marshals are interviewing witnesses and sifting through evidence as they try to figure out a cause.