RIO DE JANEIRO, BRAZIL (BNO NEWS) -- At least five people have been confirmed dead and more than a dozen remain missing after three commercial buildings collapsed in the Brazilian city of Rio de Janeiro on late Wednesday, officials said on Thursday.

The accident happened at around 8:40 p.m. local time on Wednesday when a 20-story building collapsed and crashed into two smaller buildings, collapsing them as well. It happened on May 13 Avenue in downtown Rio de Janeiro, not far from the city's Municipal Theater.

As of Thursday afternoon, Rio de Janeiro's Civil Defense subsecretary Márcio Motta confirmed at least five people had been confirmed to have been killed while 16 others remain missing. Other reports indicate that as many as 21 may be missing.

Emergency teams were quickly at the scene and evacuated surrounding buildings, but the cause of the collapse was not immediately known. Officials pointed out that the number of casualties was relatively low considering it involved large commercial buildings but took place outside of business hours.

Brazilian media speculated that the accident may have been caused by weak structures and the age of the buildings, although some reports indicate an explosion triggered by a gas leak may have been involved.

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