SAN FRANCISCO (CBS SF) -- Six people injured in a tour bus crash in San Francisco's Union Square area remain in critical condition Friday evening, according to police and hospital officials.
San Francisco General Hospital had admitted four adult men, three adult women and one minor injured in the collision as of shortly after 7:30 p.m. Friday night, hospital spokesman Brent Andrew said.
Five adult patients were listed as critical, two adults were still being evaluated and the minor's condition was not being disclosed publicly, Andrew said.
A police spokesman said six patients were critically injured in the crash.
Police and fire officials said Friday afternoon that 20 people were transported to hospitals with injuries ranging from minor to life threatening after an out-of-control double-decker tour bus hit at least four vehicles, a bicyclist and a construction site's scaffolding near Post and Stockton streets. That number was later corrected to 19.
At least five people's injuries were considered life threatening, including those of the bicyclist, according to Officer Albie Esparza.
San Francisco Fire Chief Joanne Hayes-White said three other people suffered moderate injuries but were expected to survive and 12 people had minor injuries.
Esparza said it's unclear what caused the crash but police are investigating whether it was a mechanical failure, a medical emergency or the influence of drugs and alcohol.
Esparza said the bus started picking up speed in the 500 block of Post Street, and then ran into the scaffolding and cars shortly thereafter.
It was initially reported that there were at least 30 people on board the bus, which stayed upright during the crash.
Hayes-White said crews had to extricate two people on the bus, including the driver, two pedestrians trapped underneath the bus and two people in vehicles involved in the collision.
The incident caused delays and service disruptions on bus and cable car lines in the area.
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