At least 10 Yishun flats were reportedly hit with metal ball bearings over the past nine months.

The ball bearings resulted in damaged glass doors and windows. In one case, the damage was estimated to cost about S$900 to repair.

The police are currently investigating.

The flats that were hit were mainly located on the 8th to 10th floors of HDB blocks 347A and 347B of Adora Green, Yishun Avenue 11, according to Shin Min Daily News.

A resident, with the last name Xu, told Shin Min that she had first heard of the incident from other neighbours sometime last December. And a day after hearing the news, her glass window in her master bedroom was shot three times.

Xu said that the diameter of the hole was about half a centimetre, but the impact of the ball had caused cracks that stretched three centimetres long. The hits also left glass fragments all over the floor of her master bedroom.

She called the police and they came down to her home to investigate the matter but were unable to identify where the metal ball bearings were shot from.

Xu noted that about nine other households had the same experience since last June.

Another female resident, who did not want to be named, told Shin Min that when she was working from home in December last year, she heard a series of loud bangs coming from a room in her home.

A small iron ball was later found and handed over to the police.

Another affected resident told The Straits Times that the damage to her doors is estimated to cost S$900 to repair.

Incidents happened during school holidays

Strangely, Xu said that all the incidents happened during the school holidays (June, September and December breaks), causing residents to worry about the safety of their children.

Another resident, with the last name Zhong, told Shin Min that she is worried about her 7-year-old child being shot. The window of her home has been shot four times in the past six months.

Several of the affected residents have reportedly made police reports.

The nearest buildings to the affected flats, which may be where the culprit shot the ball bearings from, are Blocks 323 and 324 Yishun Central.