A blast that shook houses in Calgary and created a large cloud of smoke was part of routine blasting at a gravel pit, according to the fire department.

The blast happened at around 1:40 p.m. MT in northwest Calgary near the community of Royal Oak, prompting chatter on Twitter about shaking homes and an investigation by emergency officials.

In a statement, Lafarge officials said staff "initiated a standard, planned quarry blast at our Spyhill site in Calgary.… Dry conditions and cold air resulted in an unusual cloud of dust. This was a routine, permitted effort."

Calgary's deputy fire chief Tom Sampson later explained on Twitter the explosion was due to "some blasting going on.... All is OK, it's a large gravel pit doing some work."