San Francisco's Department of Building Inspection is investigating after construction workers demolishing a Pine Street building sent debris onto the sidewalk and into a lane of traffic.

The empty building, located between 435 and 471 Pine Street, which is near Montgomery Street, was undergoing a planned demolition at around 8:20 this morning when, as KRON4 reports, a backhoe pushing at the top of the structure's facade sent almost the entire building crumbling down. You can see the mess in the video below.

The debris pile extended past the sidewalk and into the street, CBS5 says.

Amazingly, no one appears to have been hit by fragments of the collapsing building because, KTVU says, the Columbus Day holiday means fewer Financial District businesses were open today, so there weren't many folks on the street.

DBI and California's Occupational Safety and Health Administration are both looking into the collapse.