Fire investigators in North Carolina are trying to figure out what sparked an inferno in Raleigh Thursday night.

The six-story apartment complex which was still under construction didn't stand a chance against flames ripping through its wooden frame.

The building had been inspected 50 times during the construction process, including on Monday.

The sprinkler system and fire walls hadn't been installed yet.

Glenn Corbett, an associate professor of fire science at John Jay College in New York, says larger wood-frame construction projects are becoming more common.

He says until building codes change, these buildings will have a major vulnerability during construction.

"It's still wood," Corbett said. "At the end of the day wood still burns and that's why a lot of cities, not all cities, but older cities banned the use of wood over 100 years ago because they realized that fundamentally it could start a major conflagration - not just a building or two, but entire blocks of a city basically."

One firefighter was hurt during the blaze in Raleigh.

Multiple surrounding buildings were damaged because of how intensely the fire burned.