DENVER — Oops.

The demolition of a building in the Golden Triangle in Denver resulted in the entire structure coming down at once.

It makes for exciting video.

However, the city of Denver's Community Planning and Development Department said that it wasn't notified and that the building wasn't supposed to collapse all at once.

"When we saw the video footage we were extremely concerned for the way that the building came down," said Laura Swartz, communications director for Denver's Community Planning and Development Department.

The collapse happened on Saturday, April 6, but the city didn't find out until they were sent cell phone video.

"The contractor on the site should have told us within three days of what had happened," Swartz said. "That did not happen."

On May 16, Alpine Demolition and two of the company's principals were sent a notice that their license would be suspended.

A final order was sent on May 30, suspending the license of Alpine for six months and the certificate for James Gochis for one year. The suspensions have been appealed by both.

"It did not occur the way that it was supposed to, the way the engineer had laid out, and the contractor showed an alarming disregard for the safety of everyone else that was in the area," Swartz said.

In the suspension notice, the city wrote:

"…the collapse violated the Building Code and displayed an alarming disregard for Worker Safety, Public Safety, Traffic Safety, Environmental Safety and was an overwhelming deviation from the required closures and the engineered demolition plan."

No one was hurt when the building collapsed. In cell phone video sent to the city, someone recording can be heard asking a construction worker if the operator of the heavy machinery was OK.

"Yeah, he's out," the construction worker said, as he swept debris off the street.

"The way this building was supposed to come down was one floor at a time," Swartz said. "In this case, there were workers on site who were put in harm's way, the street wasn't closed, the sidewalks were not closed properly, there was a lot of dust from the site that should have been controlled and managed. You should not have a situation where you have people sweeping up dust from the street and from the cars nearby when the demolition is done correctly," Swartz said.

In a phone call late Friday, Gochis told Next that the collapse was a planned contingency. He said that the building was coming down that day, and because of the winds, a collapse like that was a planned option. He said the area was properly protected and that they had spotters watching when the collapse happened.

The demolition plan that was approved in October, called for the final section of the building to be torn down in a "tiered 'wedding cake' type shape so as not to leave a single 5 story free-standing bay at the end."

Gochis said by phone that the plan allowed for discretion for the demolition to occur the way it happened.

SUGGESTED VIDEOS | Local stories from 9NEWS