Fire crews from six stations across the area rushed to Whale Island Way after an emergency call at 12.16pm.
Emergency service staff instructed residents to turn off the gas and electricity to their properties before they were evacuated to nearby HMS Excellent.
Residents report that the explosion occurred in a house occupied by a couple and their teenage son, who were in the property at the time of the incident.
South Central Ambulance Service NHS Foundation Trust confirmed that they treated three casualties at the scene, with one of them – a man in his 50s – requiring treatment at Queen Alexandra Hospital for minor injuries.
A spokeswoman from the service said: ‘We sent to the scene our Hazardous Area Response Team (HART) an ambulance crew and two paramedic officers.
‘They were assessing and treating three casualties, two did not require hospital treatment however one man in his 50s was assessed and treated by our crews on scene and was taken to Queen Alexandra Hospital for treatment to minor injuries.’
A ‘singed’ man was seen escaping from the property after the blast, according to one resident.
Helen Hudson, who has lived in the road for 42 years, said: ‘A neighbour who helped them said they had to escape through the broken window at the front.
‘They were definitely in a state of shock.
‘I saw the man who lives there, and he looked singed.
‘Apparently a woman at the back of the street got blown off her feet.’
Another resident added: ‘I heard the explosion - these are old houses and they can make a lot of noise, so I thought it was kids jumping on the floor.’
Police kept the road taped off for more than three hours as firefighters assessed the damage to the property.
The incident saw crews from Southsea, Cosham, Fareham, Portchester, and Eastleigh fire stations supported by an aerial ladder platform from Basingstoke, according to Hampshire Fire and Rescue Service.