READING, Pa. – Investigators returned to the scene of a three-alarm fire in downtown Reading Thursday.

Flames damaged three buildings and forced nearly 40 people to seek help from the Red Cross.

North 5th Street Fire Reading

WFMZ-TV | Caitlin Rearden

“The fire did do a lot of damage to 113 and did subsequent, significant amount of damage to the top floor and the third floor to the building to the north,” says Reading Fire Marshal Jeremy Searfoss.

That damage looks different in the daytime as you watch clouds pass by through the windows of the now roofless buildings. Searfoss says the fire spread quickly.

North 5th Street Fire Reading

WFMZ-TV | Caitlin Rearden

“A lot of it is configuration of the building,” says Searfoss. “If you look at the back of these buildings, this courtyard design created basically a chimney which the fire developed very rapidly.”

The ATF is assisting in the investigation as authorities conduct more interviews and work to gather information about what caused the fire.

“We work hand in hand with them on a regular basis,” says Searfoss.

He tells WFMZ 113 and 115 had business spaces on the first floor and apartments higher up.

All occupants made it out safely.

North 5th Street Fire Reading

WFMZ-TV | Caitlin Rearden

The former boutique in 115 is not currently occupied but the owner of Ma Patisserie, a Cafe & Bakery on the first floor of 113, says she’s waiting to hear how bad the damage is so she can decide how to move forward.

She says she believes her space had a lot of smoke and water damage.

“Both of these buildings had limited area sprinkler systems as well as fire alarm systems, so in this instance had these not been here we would probably be having a very different conversation,” says Searfoss.

The fire marshal says he doesn’t want to jump to conclusions, and officials aren’t releasing a cause at this point.