A section of Toronto's financial district, closed after a slab of marble fell from First Canadian Place on Tuesday, was reopened before afternoon rush-hour traffic Wednesday, but it could be days before the entire area is open to traffic.

A stretch of King Street West from York Street east to Bay is expected to be closed for several days. All other roads were reopened about 4 p.m. ET.

The piece of marble, weighing about 140 kilograms, fell 60 floors, landing on the third-floor roof of a building. No one was injured.

High winds and heavy rain on Tuesday evening may have been to blame.

Inspectors will examine the building at King and Bay streets to make sure no other pieces of marble have come loose, Toronto police Staff Sgt. Jay Frosh said.

The road closures snarled traffic Wednesday in the surrounding downtown area and frustrated commuters as buses and streetcars were rerouted. King Street streetcars were being diverted between Bay and Yonge streets.

The area blocked off to pedestrians and traffic originally reached to Adelaide Street from King Street, and from York Street east to Bay Street.

Workers at First Canadian Place were allowed into the building Wednesday morning through an underground entrance.

The skyscraper, constructed in 1975, remains Canada's tallest office building at 70 storeys or 298 metres.