A group of people trapped by a fire inside the Shamrock Hotel in southeast Calgary were rescued with a ladder after fire crews saw them tapping on hotel windows early Tuesday morning.

Firefighters responded to the three-alarm fire at the hotel located at 2101 11th St. S.E. at 6:45 a.m. MT Tuesday.

Crews were able to contain the fire quickly.

Calgary fire crews broke through windows at the Shamrock Hotel to rescue five people stranded on the second floor. (Leila Beaudoin/CBC)

One person told CBC News that he had to be rescued because the fire exit was chained.

Shamrock Hotel spokesperson Darcy Clendenning said the locked fire escape was decommissioned as a fire escape five years ago when the restaurant on the second floor of the hotel was closed.

He said it was always the fire exit for the restaurant and never for hotel room patrons. Clendenning said all other fire exits were clear and up to code and the Shamrock had recently passed a fire inspection.

A total of 11 people were forced to leave the hotel and three people were transported to hospital to be treated for smoke inhalation, according to the Calgary Fire Department.

Fire crews were also forced to break hotel windows to get five of the evacuees out of the building.

"We concentrated initially on rescue when we first got here; there was a number of people pressed up against the glass," said battalion chief Larry Fisher.

"You can imagine the stress on them, and us, so the first thing we did was set up aerial rescue ladders, took out glass and took out five people from the top floor."

Fisher says two or three units were heavily damaged and there is smoke damage throughout the hotel.

The cause of the fire is under investigation.