Raleigh, N.C. — Investigators are still trying to determine what caused a fire that displaced 29 residents of a Raleigh apartment complex on Wednesday.

They also are looking at dried pine straw used mulch around the building. Although they don't think pine straw caused the Concord Apartments fire, they say it has potential to help fuel fires.

"With the humidity conditions right, with the wind conditions right, you could start a brush fire very easily," said Tim Henshaw, a fire protection engineer with the Raleigh Fire Department.

Eighteen months ago, dry conditions and wind fueled a townhouse fire started by discarded smoking materials in pine straw at the Pine Knolls Townes complex in North Raleigh. Thirty-eight units were destroyed.

City leaders considered banning pine straw near homes after the fire, but instead issued a recommendation that it be kept 10 feet away from residences.

"I have not heard any compelling reason why we should start banning these kinds of materials," Raleigh City Councilman Rodger Koopman said.

Koopman questions how such a rule could be enforced anyway, saying a rule would be too intrusive into residents' lives.

Chapel Hill leaders have banned pine straw near some commercial and multifamily buildings. The rule came after a string of fires there last year. The common factor in those fires was discarded smoking materials.