Updated 8.33pm with developer's explanation.

Glass rained from a tower under construction in St Julian's on Monday afternoon, injuring nobody but creating traffic mayhem.

The police confirmed the incident, which happened at about 4pm at the Mercury Towers complex on Gort Street, Paceville. 

An eyewitness, Phil Pearson, wrote on Facebook that the glass fell from almost 15 storeys up, with workers having continued to work despite a strong wind.

"They are insanely fortunate no one was walking past. We work in the CF building opposite and glass rebounded up onto the 4th floor balcony where we are," Pearson said.  

He said construction workers tried to manage traffic and clear people from the street while more glass parts fell.

"How is this even allowed to be moving dangerous objects in high wind over pedestrian areas? Things need to change, now," he insisted.

Mercury Towers told Times of Malta that a contractor working inside the building hit one of the already-installed windows on the 14th floor and the glass shattered, as designed when hit with some force.

"In line with international safety standards, Mercury Towers uses safety tempered glass, which is the safest glass in the industry and less likely to pose a threat when broken," the company said. It apologised for the inconvenience caused.  

A police spokesperson said that the site was cleared of broken glass and that as of 6pm traffic was flowing as normal.