Several 911 calls of heavy smoke and fire were made by people in the Coronado Towers Saturday night.
Firefighters arrived to find a fire on the second floor and immediately began to evacuate tenants.
Fire investigators tell ABC-7 21-year-old Kevin Rodriguez intentionally set the fire.
Two witnesses detained Rodriguez until police arrived and placed him under arrest.
But even with the suspect in police custody, a potential threat remains.
"There's no air movement in the building because the power is off. The air conditioning system which would of assisted us greatly in this, is out of service" said Batallion Chief Robert Arvizeu. "As a result there's carbon monoxide throughout the building," said Arvizeu.
A day later the building is without power while firefighters work on the scene to clear potentially deadly levels of carbon monoxide.
"Carbon monoxide is colorless orderless and predominantly one of the biggest killers in a fire," said Arvizeu.
That's why Arvizeu says the suspected arson is still taking up fire department resources.
"We have two crews consisting of three each so a total of six individuals," said Arvizeu.
Firefighters have been manning generators and going floor by floor ventilating the rooms until there are safe levels of carbon monoxide.
"Currently, we are on the 8th floor. Its taking approximately two hours per floor," said Arvizeu.
Meanwhile tenants have been stopping by the building wondering if they can pick-up personal items from their work areas only to get turned around by security or fire officials.