We are learning more about a deadly house fire from early Saturday morning. Four people are dead and five others were hospitalized after fire engulfed a multi-family home on Grape Street in Rochester. YNN's Kate McGowan has the latest.

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"Obviously the conditions just deteriorated incredibly quickly," said Rochester Fire Chief John Caufield.

For Rochester firefighters, the scene started out much different than its tragic ending. Upon arrival, crews discovered a rubbish fire on the property in front of the house. Chief Caufield described it as a pile of burning clothes.

Firefighters knocked on the doors, checking for people inside. They walked around the home, but after numerous attempts they did not locate anyone.

But after a second survey of the house, they noticed flames and smoke coming from the first floor. As well as two trapped inside.

"The engine company officer immediately forced entry into the apartment. His nozzle person came with him and they quickly sized up the situation and found an adult female victim and I believe a two year old in the room that was on fire," the chief said.

Both were rescued and rushed to the hospital for treatment of their injuries.

Chief Caufield said crews then received word of four trapped on the second floor.

"Heavy smoke and fire coming out of the top of the window and they were trying to get into the bottom of the window."

It was a rescue effort that Chief Caufield describes as incredibly valiant. His crew literally pushing through fire to locate those trapped.

Intense heat and flames kept firefighters from reaching the victims.

"In spite of their most heroic efforts, we had a tragic outcome here."

Once the fire was knocked down, the chief said four children were found ranging in age from below ten years old to early to mid teens.

"We've got to do some good interviews with the folks who were in the building, and who knew best what was going on inside the building that exact second."

A joint investigation is underway between the Rochester Fire Department and the Rochester Police Department. Investigators are now trying to determine what was happening inside the home at the time the fire started.

They are hoping witness statements can provide critical information they need to find a cause.

"Certainly red flags, and we want to find out what the back story is," the chief said.

But there is one certainty Chief Caufield is proud to share.

"I can't say enough how proud I am, how honored I am to be a part of this department. We got the finest firefighters in this country, and they demonstrate their value, their worth, their integrity every single day."