A large section of Saint John's uptown sits empty after a fire raged through a three-storey building early Wednesday, and police believe the fire may have been set deliberately.

Fire crews received a call around 3 a.m. Wednesday that a vacant building on Princess and Charlotte Streets had caught fire.

They say the flames began in the right section of the building and spread quickly throughout the structure.

Crews say the fire ripped through most of the upper floors of the building, making it difficult to extinguish.

Fire Chief Kevin Clifford says officials determined the building would have to be demolished after spending only two hours on the scene.

"The nature of the fire basically consumed all of the wooden material inside, so there was no structural support for the brick walls on the outside," says Clifford.

The building was only occupied on the bottom level, where a convenience store and an accounting office were located.

No one was injured in the fire but the flames also spread to an adjacent rooming house on Princess Street, forcing out 22 tenants.

Those who live nearby were woken up by the sound of alarms and flashing lights.

"Came out about 3:30 this morning and the flames were just shooting sky high and very vibrant red and orange in colour, just straight up," says area resident Karen Doyle.

The Canadian Red Cross says it is helping the tenants to find emergency lodging until they can make other arrangements.

Forensic officials were on site early Wednesday afternoon to photograph the inside of the building to determine the cause.

With files from CTV Atlantic's Ashley Dunbar