Officers are still at the centre and are examining CCTV footage, a sign-in guest list - which is required under COVID-19 protocols - and speaking to people who were in the area at the time of the incident.

Initial inquiries suggested the girl was sexually assaulted by an unknown man, but Detective Superintendent John Kerlatec Child Abuse and Sex Crimes Squad Commander said the girl's young age made the situation complex.

"Due to the tender age of the child... we're going to keep a very open mind and treat this as its worst," he said.

"A child between two and three can only provide so much information.

"We're going to work the rest around what other people have seen and heard, and any other evidence we can identify."

Anyone with information about the incident, in particular people who were at the play centre on Sunday and may have witnessed suspicious behaviour, is urged to contact Crime Stoppers.

Lollipops was closed on Monday and were set to reopen on Tuesday, a note on the centre's Facebook page said.

"As parents of young children ourselves we are devastated for the family involved and are fully cooperating with the police investigation, our centre remains closed temporarily. The safety of our customers and staff is always paramount. We thank you all for your support and understanding in this difficult time," the Facebook post said.

If you have an information you can contact Crime Stoppers on 1800 333 000.