A stone-throwing vandal cracked the glass panels in a roof above a pre-school, causing concern among some parents about their children's safety.
Many had not been aware that the Fusionopolis branch of MindChamps, in Buona Vista, had been targeted by a mystery culprit in a string of recent attacks.
When The Straits Times paid a visit on Tuesday, there were six large cracks in the roof of the pre-school, which is on the third floor of the building.
One of the pre-school's vertical glass panels shattered on Sunday, though this is believed to be due to a manufacturing defect. The glass shards were removed and the pane was replaced early on Monday morning.
The pre-schoolers present at that time - who normally walk barefoot - wore slippers as a safety precaution.
Most parents said they were unaware of the matter. One mother told The Straits Times on Tuesday that she had not been informed of the incidents but was "very worried".
The woman, who declined to be named, said the pre-school staff have always been cooperative. "I hope they will stop the kids from playing near the affected areas if it is really unsafe."
Nobody was injured in any of the incidents.
JTC Corporation, which developed Fusionopolis, said a glass specialist inspected the cracked roof and "concluded that the roof is still structurally sound".
A spokesman said the roof is made of double-glazed tempered laminated glass that "will prevent any cracked glass from falling".
Commenting on the shattered panel, she said JTC had sent a contractor on Monday morning to inspect the place before the pupils arrived. She added that JTC has been in regular contact with MindChamps on both incidents.
A source told The Straits Times that it appears that the culprit, who has not been caught, has been throwing pebbles from the sky garden on the fifth floor down onto the pre-school's glass roof. All pebbles have since been removed.
It is understood that no police report has been made.
However the pre-school may have to wait some time before the panes are replaced as a crane will have to enter a construction site next door. The Fusionopolis management will have to arrange with the construction company a suitable time to do this.
A parent, who wanted to be known only as Mr Wong, 41, said he saw some people checking the roof yesterday morning.
"I saw the cracks too, but they seemed restricted to just one area," he said. "I'm not too worried about it but I hope they will come up with something to fix it."
A MindChamps spokesman said the pre-school "has been assured by the building management of Fusionopolis that the glass is double-layered and hence safe". He said the building's management will write to parents to inform them about the cracks.