Raleigh, N.C. — A improperly discarded cigarette sparked a fire that tore through a Raleigh apartment complex, investigators said.

The fire started just after 6 p.m. Saturday at the Governors Point Apartments on Lake Lynn in Building 3211.

Of the building's 20 units, fire, smoke or water damaged 18.

Investigators said Sunday that a cigarette in a balcony flower pot started the fire.

"It is amazing how expensive they [cigarettes] get these days," fire witness Michael Hendrick said.

Hendrick lives a couple buildings down from the fire. When he came home Saturday, he said a massive cloud of smoke swirled around police and firefighters.

"The whole parking lot was drenched in a thick fog of black smoke. You could see spotlights coming down from the fire engine ladders," he said.

Hendrick said that the huge flames made it hard to believe that no one was injured.

Four firefighters were briefly trapped when a ceiling collapsed. They were able to make their way out of the building safely, however.

The Red Cross is helping 20 displaced residents. A dog was still missing Sunday afternoon, and it was not known if the pet perished in the fire.

Hendrick said renter's insurance is required at the Governors Point Apartments. That coverage will help as displaced residents look for new homes and possessions.