Nearby residents told Scotland News the explosion sounded like a “sonic boom” when it happened at the two-storey block of flats on Sunday night around 18:00.
A rest centre that was set up at Alloa Town Hall after the incident has now closed, with those affected having found accommodation with friends and family.
Two men, aged 72 and 19, and a 49-year-old woman were taken to Forth Valley Royal Hospital for treatment.
The area’s MSP Keith Brown said there was a “sense of shock” in the community.
He said: “I can’t see that particular street being used until it’s made completely safe, and that includes the future of the house that’s been the subject of the explosion.”
He added that as well as the emergency services, rail authorities had also attended the scene, because the site is on the bridge of the local railway.
CCTV footage recorded by a nearby restaurant captured the moment of the explosion.
A number of locals were reported to have rushed to the scene to try and help.
