A man, a woman and four children died after flames tore through a Pennsylvania home overnight.

And Kelly Brown, the mother of the four kids, witnessed the Mother's Day blaze, according to a friend.

Schuylkill County dispatcher Bill Lindenmuph told NBC10 that the fire broke out just before midnight at a single-family home on the 200 block of Pierce Street in Pottsville, Pa.

Pottsville Fire Chief Todd March called it the worst fire he has seen in 37 years battling blazes.

"By the time our firefighters arrived on the scene there were flames everywhere -- coming out the front -- the whole building was entirely engulfed," said March.

Firefighters later found all of the bodies on the third floor of the building, which sits on a steep hillside not far from the D.G. Yuengling & Son brewery in Pennsylvania's coal country, about 90 miles northwest of Philadelphia.

The Schuylkill County Coroner's office identified the victims as Eric Brown, 30; and his children, Elijah Brown, 2; Emily Brown, 3; Jeremiah Brown, 7; and Joy Brown, 8.

Kristina Thomas, 26, also died. She's the sister of 28-year-old Kelly Brown, the mother who survived.

Kelly Brown had been doing laundry at a neighbor's house nearby at the time of the blaze because her washing machine was broken, according to the neighbor, Jennifer Purcell. Purcell said they had smelled smoke, and Purcell went outside and saw the flames, telling Brown, "Oh my God, your house is on fire!"

They both ran up the street to the house, but weren't able to get inside, Purcell said.

Kelly Brown started screaming to emergency personnel keeping her back, "What do you mean I can't go in? My kids are in there, my husband is in there, my sister is in there. I've got to get them," according to Purcell. Brown got weak after that and had to be walked down the street because she couldn't stand, Purcell said.

Video shot by FireandFilm.com shows heavy flames shooting out of nearly every window of the home as firefighters try to battle back the flames.

Five firefighters suffered minor injuries trying to rescue the family and put out the fire. Two remained hospitalized Monday morning.

It took firefighters about an hour to bring the fire under control. All seven stations from the Pottsville Fire Department as well as surrounding departments were on location, Lindenmuph said.

Kelly Brown is distraught over the loss of her family. She is staying with her husband's relatives elsewhere in Pottsville.

"She's a wreck," Purcell said. "Not only did she lose, as she said, her best friend, her husband, her kids, but it also happened on Mother's Day."

The cause of the fire remains under investigation. A fire official told Zachry that it appeared the fire may have started in the kitchen.

Fire officials said ti doesn't appear that there were working smoke alarms in the home.