A woman broke the window of a Darwin, Australia, childcare center with a brick when she arrived to find the building locked, the lights out and her tiny son trapped inside.

Yula Williams, 30, said she could hear her eight-month-old baby Xavier "screaming and crying," the Northern Territory News reported.

"It made me terrified to know that my son was inside the center, locked and in the dark," she said.

Williams had dropped her son off at the center in the Darwin suburb of Wagaman on Tuesday morning and went to work.

She had dropped her car off at a local mechanic and arranged for one of her cousins to collect her son from the center before it closed at 6 p.m.

But the arrangements fell through close to the day care's closing time, so she tried to call, but the phone kept going to voicemail

"We got here at 10 minutes to six, everything was locked up," she said.

After scanning all the security screens the frantic mother climbed the back of the building to call Xavier's name.

"I couldn't hear him from the outside but when I walked around and called through the vents to the bedrooms I heard him scream," she told ABC radio in Darwin.

Desperate to get to her tiny son, Williams then picked up a brick from the garden bed and smashed it through a window.

Police said they were continuing to conduct investigations into the incident.

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