A total of 44 people from a dozen families have been displaced from their homes Sunday following what authorities are investigating as a possible explosion in Allentown.

Around 3 a.m. Sunday morning, residents were awakened by a loud noise followed by heavy black smoke and flames visible, according to city police and fire officials. Allentown Fire Capt. John Christopher said the incident began inside a home at 726 N. Fountain St.; it remains unclear if something actually exploded leading to the blaze.

Crews are working to find some pets that are unaccounted for, according to Christopher. A man initially unaccounted for has since been found, who was determined not to be home at the time of the blast, he said.

A row of homes from 714 through 732 North Fountain Street were damaged; at least 10 structures are being readied for demolition, Christopher said Sunday afternoon. A total of 30 people from eight families are displaced and another 14 people from four families have been evacuated from 918 Green St. and 713 N. Fountain St. as a “precautionary measure,” he said.

“It’s a mess right now,” Christopher said from the scene of rubble.

There are no ongoing safety concerns, but the public should avoid the area, city police stated in a tweet.

UPDATE: The unaccounted person from this morning's incident has been located safely. The investigation continues into the cause and origin of this possible explosion. There are no ongoing safety concerns. Stay clear of this area #AllentownPolice — Allentown PD (@AllentownPolice) October 20, 2019

The cause of the explosion remains under investigation. Crews arriving on the scene didn’t initially detect an odor of natural gas, according to Christopher.

Two Lanta buses are being used as a temporary shelter.

WFMZ-69 News reported a firefighter sustained a shoulder injury while fighting the blaze, and was taken to the hospital. He has since been released.

We have a team of Red Cross disaster responders currently heading to the scene of a house explosion and multi-family fire in Allentown this morning. — Red Cross Eastern PA (@RedCrossPhilly) October 20, 2019

The Greater Lehigh Valley chapter of the American Red Cross is working to assist all the displaced families.

Five people in February 2011 were killed in Allentown in a natural gas explosion along the 500 block of North 13th Street in Allentown. A 79-year-old man, 69-year-old woman, 16-year-old girl and 4-month-old boy were among the deceased. In the end, the blaze destroyed eight row homes.

Pamela Sroka-Holzmann may be reached at pholzmann@lehighvalleylive.com. Follow her on Twitter @pamholzmann. Find lehighvalleylive.com on Facebook.