At least four people were killed when a Jordanian policeman opened fire at the facility near the capital city of Amman, according to Jordan's state news agency.
Arab youths dissatisfied with the present are looking longingly to the past, and Islam's glory days. That, and a dearth of opportunities, says Jordanian politician Rula Alhroob, make ISIS attractive.
The government says free expression can combat radicalization. Yet a military court recently sentenced a man to 18 months in prison for a Facebook post deemed insulting to the United Arab Emirates.
Jordanians now support the military campaign against the self-declared Islamic State. But King Abdullah still faces domestic opponents, religious and secular, who chafe at restrictions at home.
A defense official tells NPR that the rebels will be vetted and screened under top-secret protocols. Qatar, Jordan and Saudi Arabia will also be part of the effort.
Repeated airstrikes on the self-described Islamic State are "the beginning of our retaliation" for the extremist group's brutal killing of a captured pilot, Jordan's foreign minister says.