A couple have been charged with manslaughter and police are searching for another woman after a security guard was allegedly fatally assaulted while trying to stop an attempted break-in at an inner-city Sydney shopping centre.

Witnesses told police a 28-year-old Maroubra woman, a 33-year-old Randwick man and another woman allegedly punched and kicked the security guard, 68-year-old Hans Schulz, after he interrupted them during an alleged break-in at the Wendy's ice-cream kiosk in Broadway Shopping Centre last night.

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Police said the group, who were with two children, aged three and five, then fled the centre. They identified the woman for whom they are searching as Raelene from nearby Surry Hills.