Are airport police empowered to make arrests?

I was surprised to read that the woman who was abusive and assaulted the Singapore Airlines employee was arrested only the next day (Woman jailed for throwing sign at SIA employee; July 25).

Her violent and abusive behaviour had injured the victim and happened in plain sight of witnesses at the airport, a place with high security.

Why was she not arrested on the spot instead of being allowed to wander free in our country?

This brings to mind a similar case not too long ago, when a foreigner arriving at Changi Airport was abusive towards our airport police, but was allowed in anyway, only to be subsequently arrested for committing other offences in Singapore.

Should we not take a sterner stance at our borders? Are our airport security officers empowered to make arrests?

Yeo Yujin