CHARLOTTE, N.C. -- A four-alarm fire started at a south Charlotte apartment complex at about 3 a.m. Tuesday. At least 75 firefighters worked through the morning to contain the fire and smoke.

Crews evacuated all 66 units at the Charlotte Woods Apartments, located off Scaleybark Road.

Power won’t be restored to the units Tuesday, officials said. The American Red Cross opened shelter at 5 p.m. Tuesday for all of the people displaced by the fire. The shelter is at E.E. Waddell High School at 7030 Nations Ford Road.

Red Cross officials estimated that the disaster response to the fire will cost the chapter more than $30,000. That covers the cost of providing food, clothing and shelter on a case-by-case basis for the people who were affected.

Firefighters had to use chainsaws to cut through the roof of the complex to get access to the fire. They also broke windows to release smoke and heat from the apartments.

•SLIDESHOW: Fire Rips Through South Charlotte Apartment Complex

•VIDEO: Red Cross Opens Shelter After Devastating Apartment Fire

Crews rescued at least six people from second- and third-floor balconies at the complex.

Medic treated a few tenants for minor injuries. No one suffered serious injuries.

Investigators said the fire was accidental, and believe it was started by a cigarette discarded in a storage unit that’s located at the core of the building.