Fire crews were called to a blaze at 40 Kennishead Avenue in Glasgow's South Side at about 4.30pm yesterday, where they found two people trapped in a smoke-engulfed flat on the fourth floor.
The 80-year-old man was taken to the Victoria Infirmary and treated for smoke inhalation.
Firefighters wearing breathing apparatus entered the building and led the two other casualties to safety.
They were treated for smoke inhalation at the scene by paramedics.
Crews from Clarkston, Pollok, Castlemilk and Barrhead tackled the blaze which left several floors engulfed in smoke.
The fire caused some damage to neighbouring properties.
The block was not evacuated but residents were offered hot food in a nearby hall.
Firefighters were at the scene until around 8pm as they worked to clear the smoke and ventilate the building.
Scottish Power were called to the building to turn off the electricity supply.
Police are treating the incident as "wilful fire-raising."
A spokeswoman for Strathclyde Fire and Rescue said: "Fire crews were called to a multi-storey block in Kennishead Avenue at 4.30pm.
"Two casualties were rescued from the building by crews wearing breathing apparatus.
"There was considerable smoke logging on several floors of the building.
"Fire crews from four stations attended. With a multi-storey fire we have to take additional precautions."
A spokeswoman for Strathclyde Police said: "An electrical power box was set on fire at 40 Kennishead Avenue. We are treating the incident as wilful fire-raising.
"The fire caused some damage to nearby properties.
"Inquires are continuing.
Hazel Young, GHA's south area director, said: "We're doing everything we can to help the residents affected by the fire.
"We're also working closely with the police and fire services as they continue their investigations."
The tower block, owned by GHA, is being reviewed for possible demolition in 2015.
At a community council meeting this month police said 47 crimes had been reported in the Carnwadric and Kennishead area.
These included a number of wilful fire raising incidents in Kennishead.