The storm ripped down scaffolding workers were using to add final touches to the Jose Figueroa Olympic Stadium, toppling the metal onto cars below.

"At the moment we have information that give people are injured and the meteorologists have told us they expect two smiliar episodes during the afternoon," police spokesman Francisco Carbo said.

Five people were injured - none seriously  - but officials evacuated people who had already arrived at the stadium which is close to the shore on Puerto Rico's western coast.

Felipe Perez, President of the Games Organising Comittee, said he was taken aback by the storm's strength.

"The wind was like something out of a movie," he said.

The ceremony, featuring more than 5,000 athletes from 31 countries countries, was postponed until tomorrow.

Competition in the Games is scheduled to start tomorrow and run through until August 2.