Vancouver's sole NPA city councillor is calling for a public inquiry into what went wrong when a planned building demolition toppled two separate walls onto busy streets on Thursday.

Suzanna Anton told that Mayor Gregor Robertson, "really needs to step forward and give the public confidence" by appointing an independent consultant to investigate the demolition of the former William Davis Centre for Acting at the corner of Hornby and Helmcken streets.

Hundreds of pounds of rubble spilled onto the road when the north wall collapsed into the street, shooting clouds of dust and debris into a car stopped at a nearby intersection.

Shortly after, a second wall fell, toppling a light standard and narrowly missing a flag person standing on the road. Miraculously, no one was injured in either collapse.

"It was, of course, extremely dangerous," Anton said.

Videos of the two walls collapsing were posted on YouTube, where they have each garnered more than 120,000 views.

Anton said that the videos are "damaging Vancouver's reputation," and added that a public inquiry into safety measures at the demolition site would reassure the public that measures are being taken to prevent similar incidents.

"I do not propose a long, complicated inquiry," she said. "But we need someone to get to the bottom of it quickly and efficiently."

Both the City of Vancouver and WorkSafe BC -- which can fine the developer or the demolition company up to $519,000 -- are already investigating the incident.

Pending the outcome of the investigation, Vancouver's chief building official Will Johnston said the city has "shut the site down and asked that they stop construction."

Global Excavation and Demolition, the company hired to tear down the building, has declined to comment.

The property is the future location of high-end condo development Hornby Residences. Project manager Cairan Mulhall said the lanes surrounding the building were blocked off during the demolition, but that the city did not allow crews to close off the street entirely.