MEXICO CITY -- A roof garden installed on top of a newly opened shopping mall on Mexico City's south side may have caused part of the structure to collapse.

The Mexico City prosecutors' office said late Thursday that planters used in the roof garden added excess weight that apparently contributed to the collapse of a cantilevered section that stuck out from the building.

The mall's operators quickly evacuated the area Thursday after a support beam failed. About five minutes later, the top floors collapsed. No injuries were reported.

The city has promoted the installation of roof gardens, in part for their supposed environmental benefits.

The Artz Pedregal mall opened in March, though parts remain under construction. Built on the edge of the city's main expressway, the mall had suffered previous subsoil slides.