RIO DE JANEIRO, April 12 (Xinhua) -- At least five people were killed and 13 others missing after two residential buildings collapsed Friday morning in a poor area in west Rio de Janeiro, Brazil's civil defense authorities reported.

The two collapsed buildings, both opened six months ago in the Muzema slum community, were irregular constructions built without the permission of the Rio city authorities.

The residential use of the two buildings had been prohibited twice, in November and February. They were not demolished due to the danger demolition presented to adjacent buildings.

The Rio city authorities announced on Friday that it would demolish three buildings adjacent to the collapsed buildings, which were also built without a license, to avoid the risk of more collapses.

The Muzema community is controlled by violent mob-like militia groups, which act as mafias. The two buildings are likely to have been built by order of those groups.

It is estimated that in the same community, there are about 60 residential buildings built without official permits for construction and sales.

The Muzema area was deeply affected by the strong seasonal rain and wind which hit Rio earlier this week and left 10 dead and caused severe damage. But it was not raining when the collapse occurred.