A Monday morning mishap with what appears to be a tech bus smashed up at least four cars on Castro Street near 20th Street, with pictures and video starting to emerge on social media.

San Francisco has pretty much gotten over its outward animosity toward tech buses, but a handful of people who were parked on Castro Street Monday morning have fresh reason to be resentful of the tech bus shuttles. A Monday morning Reddit post asking “Why have the police closed Castro Street?” brought numerous commenters saying things along the lines of “A tech bus plowed down the hill backwards through a bunch of traffic.” KPIX has confirmed that a commuter bus struck multiple vehicles on Castro between 20th and 21st streets, and adds that at least one person was injured.

Someone posted the aftermath video below saying, “A google bus lost its power while going up the hill and roll back and hit 9 cars this morning outside of my place.” We cannot confirm the commuter bus had any affiliation with Google, and KPIX says “at least four vehicles” suffered major damage in the incident.

A Monday morning Citizen post from 8:49 a.m. said “Police have received a 911 report of a bus that slid down a hill colliding with multiple vehicles when it's brakes failed.” That seems to square with KPIX’s reporting that “the collisions happened at around 8:45 a.m.”

The SFMTA acknowledged that a “non-Muni collision at Castro/20th” had caused some disruptions along the 24 bus lines in that neighborhood.” Though the agency tweeted at 12:20 p.m. that the 24 line had resumed full regular service.

KPIX reports that one person was hospitalized with undisclosed injuries. That station also notes that “It appeared the bus may have rolled backward on the steep hill and into multiple cars,” though the police have not yet commented on any possible cause of the accident.

If you have any information on this incident, you’re asked to call the SFPD Tip Line at (415) 575-4444, or Text a Tip to TIP411 and begin the message with “SFPD.”

This is a developing story and may be updated.

Related: Shuttle-freude: Genentech Bus Accident Closes Four Lanes Of Divisadero [SFist]

Image: @DavidGallagher via Twitter