Images from Chopper11 HD show several fire and emergency crews responding to the scene.
Firefighters say two units were completely destroyed, two have significant damage and two others have smoke damage and are uninhabitable.
Officials say at least 12 adults and 12 children are displaced. The Red Cross is assisting residents who need somewhere to stay temporarily as well as those whose units are no longer livable.
Resident Brenda Hyman says she is grateful to neighbors who banged on her door to let her know about the blaze.
"I'm glad, you know, I actually got out, you know, they woke me up," she said.
One firefighter was injured and others were checked for heat exhaustion and dehydration.
Fire investigators say the blaze was accidental. Some residents say it started on the ground behind the townhomes.
Monday's fire was the second at the townhomes. Officials say lightning started a 2006 fire.
According to a fire report, the units that burned had smoke detectors, but not a sprinkler system.
Coincidentally, Raleigh fire officials and other firefighters from around the state are at a Building Code Council meeting Tuesday in Raleigh. Firefighters are pushing for mandatory sprinkler systems.
Raleigh fire officials at the meeting say Monday night's three alarm blaze at Green Castle is perfect example of the need.
"It would have helped us greatly," Asst. Raleigh Fire Chief Larry Stanford said. "Instead of losing six units most of the time, 90 percent of the time, the fire is contained to the area of origin."
But some of those who would have to pay for the expensive systems --namely builders, developers and other real estate interests-- aren't convinced they're a good idea.
The chairman of the council says he knows their concerns, because he's a residential contractor in Wake County.
"We've got to find some level of acceptance and some level of palatability in terms of affordability," NC Building Code Council Chairman Dan Tingen said. "That is a key component as well as life safety."
But hearing firefighters say a sprinkler system might have spared all but the unit where the Green Castle fire started.
"I think it would be great, because, you know, that could save someone's life," Hyman said.
But the chairman of the building code council says it's not as simple as how much a life is worth. He says affordable housing is also important.
The proposed changes in the building code, if passed, would take effect in 2012.