Vandals smashed windows in 15 public transit bus shelters across London's north-end, shattering some 40 panes of glass in a vandalism spree that happened sometime over the city's Pride weekend.

It's the kind of destruction that seems to be a quasi-regular occurrence in the city, according to London Transit Commission General Manager Kelly Paleczny, noting that a similar incident tends to happen every 12 to 18 months.

"About 18 months we had something similar to this happen. Over a three or four day period we had a whole bunch of them taken out and unfortunately in that last scenario as soon as they were replaced they were broken again," she said.

Paleczny said replacing the glass in a bus shelter can cost anywhere from $2,000 to $4,000 depending on how many windows were broken.

'Some guy goes on a rampage'

Contractors clean up and replace windows in a London Transit Commission bus shelter Monday, after they were smashed by vandals sometime over the weekend. (Colin Butler/CBC News)

In this case, it's taken about two days to not only clean up all the shattered glass inside the bus shelters, but also replace the windows, according to Feris El-Ejel of Lambton Glass and Mirror.

"We started yesterday," he said Monday

El-Ejel said his colleague Tyler Campbell had already installed at least 25 windows in LTC bus shelters throughout the Masonville area by late Monday morning.

"They keep calling us saying there's more. We had 33 this morning and then they said there's seven more," he said, noting while not common, jobs like this are also not unusual.

"You usually get something like this once every year, once every two years, some guy goes on a rampage."