An excavator working at the site of a building demolition on Spring Garden Road in Halifax fell through a floor to the level below Monday afternoon.

The excavator was working on the second floor of the building when it crashed through to the ground level.

"All of a sudden, boom! The excavator just went right down," said eyewitness Ross Stillwell.

The building that used to house a mattress store on Spring Garden Road, opposite the Halifax Central Library, is the site of the demolition. (Submitted by Geoff D'Eon)

Halifax Fire initially said there was no one in the excavator, however the provincial labour department says someone was inside but wasn't injured.

Halifax Fire did say that they believed a man at the construction site was hit by debris but was not injured.

Stillwell was watching the demolition with his father who works as an excavator operator and they saw the incident occur around 12:20 p.m. He said he believed the excavator fell about 15 to 20 feet.

He says it was a scary thing to watch.

"I was worried about the man in the machine and whether he was going to get out alive," said Stillwell.

As a result of the fall, the excavator is now in this position. (CBC)

​Andrew Preeper, a spokesperson with the provincial labour department, says the contractor working on the project voluntarily stopped work at the site as a result of the incident.

The excavator involved was stabilized and debris and other materials were removed, in a plan that was approved by department officials.

Preeper says work can now continue on the site.