A signboard of a gaming centre in Hong Kong's Nanking Street fell and injured three pedestrians on Tuesday afternoon. Photo: Google Maps

A falling billboard in Hong Kong’s Yau Ma Tei district gashed three passers-by on Tuesday afternoon, with at least one of them in critical condition with severe head injuries and requiring treatment in an intensive care unit at Queen Elizebeth Hospital.

Police arrested the 50-year-old manager of a gaming center in Nanking Street who was the owner of the 6-meter-long signboard, weighing 135 kilograms, that came loose and dropped on to pedestrians.

Scores of shattered bricks and chunks of concrete also tumbled down, some as big as a person’s hand, Sing Pao newspaper reported.

The affected portion of the sidewalk was cordoned off, where rusty rebars were hanging from the above.

A minibus driver who witnessed the incident told Oriental Daily News that the whole street was shrouded in dust after the signboard crashed to the ground, and for a few seconds he thought a building may have collapsed.

Concrete spalling and exposed bar tendons are common in aging, dilapidated tenement blocks typically seen in Hong Kong’s old districts. Between 2014 and 2016, the Buildings Department issued some 1,600 removal orders and notices regarding loose concrete, mosaics and billboards that might have posed a threat to the public.

In May, a woman was injured by a falling wooden signboard in Sham Shui Po, and in August a couple were hospitalized after being hit by shards of glass caused by a loose canopy in Kwai Hing.

Lawmakers have been prodding the authorities to launch a mandatory signboard-inspection scheme, similar to a window-safety program currently in place.