Carrying on school property

[Rumline]

There's an elementary school near my house and I'll often take my non-school-aged kid there on the weekends to play on their playground. There's always a number of families/kids there playing so I figure it's fine to use their facilities outside of school hours.

The other day I was there with my kid and I saw another parent roll up who was obviously carrying. He had a button-down shirt tucked into skinny jeans. I noticed the clips from his Crossbreed holster on his right hip and mag carrier on the other side, plus the corresponding bulges. I thought it was funny because other than the gun he looked like a hipster, complete with Prada sunglasses that he wore despite the sun already being below the horizon.

Anyway I didn't think it was legal to carry onto school property even with a permit, regardless of if school is in session or not. Is that correct? My purpose is not to narc on the guy; seeing him just made me wonder about the legality.