A Sydney childcare chain has been targeted with a second suspicious fire in four days.

Detectives are looking into whether a blaze at Play to Learn’s facility in Castle Hill in the early hours of Monday morning is linked to a fire at the company’s centre in Turramurra on Friday.

NSW Police said officers responded to reports of a fire on Excelsior Avenue, Castle Hill just after midnight on Monday.

Police behind police tape at a fire in Castle Hill

Police at the scene of the fire at Learn to Play in Castle Hill on Monday. (ABC News: Liam Patrick)

“NSW Fire and Rescue are on scene and have extinguished the blaze. There has been minor damage caused to the building,” NSW Police said in a statement.

“Officers attached to The Hills Police Area Command have established a crime scene and are investigating the circumstances surrounding the incident.”

It comes after emergency services responded to similar reports of a fire breaking out at the Play to Learn childcare centre in Turramurra on Friday.

Burnt item in front of burnt-out at scene of suspicious fire at Turramurra childcare centre

The doorway of the Turramurra childcare centre was damaged on Friday. (ABC News)

Police last week said a small fire at the business on the Pacific Highway about 4:25am caused minor damage. 

Police said a group of masked men were seen on CCTV entering the building, pouring and accelerant before setting it alight and fleeing last Friday.

The chain has a third centre in Toukley, on the Central Coast, which opened last year.

Fire authorities investigate suspicious fire in dark, burnt out doorway of Turramurra childcare centre

Authorities are investigating a suspicious fire at a Turramurra childcare centre on Friday. (ABC News)