Running from security guards, what jurisdiction and grounds do they have?

Me and some of my friends were skateboarding in a multistorey carpark “stacker” going down the levels until security rocked up and called the cops and confiscated one of my mates boards. We bolted from them before they could do much. Just curious. In a public carpark, what laws might I be braking and would I be prosecutable for skateboarding inside it?

Note- this is Australia.