Four people died in a fast-moving apartment fire in Emmaus, Pa., on Sunday.

The fire began around noon at a house on South 5th Street that was converted into apartment units. While firefighters eventually controlled the blaze, the coroner's office was called. Officials say they found four bodies in inside.

"I live right down at the corner and I did see them pulling people out," said local resident John Lake. "They did have body bags out."

The victims were not identified.

The American Red Cross Greater Lehigh Valley Chapter assisted two families who were displaced by the blaze.

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Investigators have not yet revealed the cause of the fire. Residents who live nearby say they heard explosions shortly after the blaze began on the ground floor of the building.

"I heard that it could've been gas-related," said Scott Schwartz. "The explosion came out the front window. Twenty minutes after that the roof was on fire."

Kelly Furlong told NBC10's Daralene Jones that the building was once a funeral home that her family ran until it was converted into an apartment complex.

"It was always home to me," said Furlong. "It's home and it's gone."

Michael Aldinger helped rescue some of the victims of the fire. He says that while he would've liked to do more, the smoke got to be too much.

"I tried helping them but there was too much black smoke," said Aldinger. "I heard a couple people screaming inside the house."

Police were investigating the cause of the fire Monday morning.