When asked by ATC, the pilots mention the threat level escalated to a 4 (at 2:39).

I wasn't familiar with this scale so I looked it up, it's from the International Civil Aviation Organization (ICAO):

    Level 1 — Disruptive behavior (verbal)
    Level 2 — Physically abusive behavior
    Level 3 — Life-threatening behavior (or display of a weapon)
    Level 4 — Attempted or actual breach of the flight crew compartment