HONG KONG - A runaway school bus with no one aboard accelerated downhill and plowed into pedestrians in Hong Kong on Monday, killing two people and injuring a dozen others, authorities said.

Dash-cam video from another vehicle, posted online by the Apple Daily newspaper, shows a man who appears to be the driver standing outside the bus, closing the door and then running in front of it as it starts to roll away.

The 62-year-old driver attempted to block the bus but was dragged for 20 metres (65 feet) as it gained speed, police said. The bus crossed a bustling thoroughfare, slammed into two taxis, and ran onto a sidewalk and into a store.

Three people were pinned under the wheels of the yellow 19-seat bus. One person was pronounced dead at the scene, a fire department spokesman said at a news briefing. Six of the 12 injured are in critical condition, including the driver, who has been admitted to an intensive care unit, police said.

The driver had just finished his last shift shortly before 2 p.m. The hand brake appeared not to be engaged, police said. Authorities are investigating.