Glass has again fallen from a high-rise building in the city’s downtown core this morning.

Just before 6 a.m. Thursday, Toronto police shut down Bay Street in both directions after tiny fragments of glass fell from the Sick Kids Centre for Research and onto the ground below.

Crews were spotted using machinery to vacuum shards of glass from the sidewalk shortly after.

The incident comes on the heels of a similar report of glass falling from the same building around 5:30 p.m. yesterday.

In that instance, a pane of wall glazing broke free from the building and shattered on the sidewalk.

Nobody was injured in either incident as a result.

Building officials are now trying to determine what caused the glass to come loose in the first place.

“There could be several factors there, there could be errors in installation, isolated incidents, sometimes in the manufacturing there’s impurities called nickel sulfide which can cause failures in tempered glass,” Mario Angelucci, the city’s deputy chief building official, told CTV Toronto. “(But) those are rare occurrences.”

He added that falling glass poses very little risk to the public.

"These buildings comply with the building codes. The glass is temporary glass, also known as safety glass, so when there is a failure that occurs, the glass falls or fails in very small pieces and there isn't a significant risk to the public," he told CP24.

Earlier this month, city inspectors were ordered to complete a safety review of a downtown building located on Simcoe Street after a pane of glass fell from the 26th floor.

At an unrelated event Thursday, Toronto Mayor John Tory called on city building staff as well as development and construction experts to investigate the incidents and come up with preventative measures.

"It's not satisfactory and it's not safe," he said. "Is there a problem here that is, say, related to glass manufacturing or glass installation or the way buildings are being constructed?"

Pedestrians in the Bay Street area this morning expressed concern about the incident happening more than once.

“We’re building more buildings in Toronto than any other North American city and I just trust that they’re sturdy and not going to fall,” one pedestrian told CTV Toronto.

Bay Street was closed off for several hours as the area was inspected. All lanes have since reopened.