Fire crews were called to the 200 block of Chestnut street just after 4 p.m. Sunday.
The flames started at 261 chestnut, then spread to houses on either side.
Firefighters and neighbors say strong wind helped the flames spread quickly.
"That fire kept jumping from one roof to antoher, it took out three apartment buildings across the street," said Richard Stahl.
"Next thing we knew you couldn't see anything up and down the street. You couldn't even see the firetrucks up the other (cover rest with vids of firetrucks) end of the street because the smoke was getting that bad at points," said Jo Tressler.
A fourth building also suffered some damage.
No one was hurt in the fire.
A fire marshal is expected on the scene to determine the cause of the fire in Northumberland County.