Fayetteville, N.C. — A two-alarm fire destroyed or damaged 12 units and displaced 21 residents of the North Crossings Apartments Thursday morning.

A fire broke out in a three-story building at the apartment complex on Ramsey Street, north of Methodist University, shortly before 8:30 a.m.

"It was really high," Wendy Bathke, the owner of a nearby business, said. "The whole of the apartment building was engulfed."

No one was injured, but the roof of the building collapsed, police said.

All 12 units in the building – 10 of which had tenants – can no longer be occupied, police said. Three apartments  were destroyed, and another seven sustained heavy damage, Red Cross officials said.

Soldiers, police officers and 20-something students at Methodist University were among the 21 residents displaced by the fire. The Red Cross, apartment complex and relatives were helping them find temporary housing.

"You just felt sorry for the people that were there," Bathke said.

A woman who identified herself as the property manager demanded the media leave. She said no residents were interested in talking with reporters.

One resident, police officer Russell Hickman, declined to do an on-camera interview, but told WRAL his story.

Hickman and his 5-year-old son were sleeping when the fire woke him. He grabbed his son and ran through the building, kicking open doors to make sure everyone got out.

Hickman's pregnant wife was at work – as an administrative worker at the police department. She overheard the call saying that her apartment home was on fire.

The Hickmans were among those whose apartment was destroyed.

Fire officials said they do not know what started the fire or where it originated.

The State Bureau of Investigation and federal Alcohol, Tobacco and Firearms have joined the investigation.