As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NOTICED AN UNCOMMANDED INCREASE IN CABIN ALTITUDE ABOUT 1000 FPM. PROCEEDED TO FOLLOW THE ABNORMAL CHECKLIST PAGE 3-510-10, CABIN ALTITUDE AMBER MESSAGE. UPON REACHING IF CABIN ALTITUDE IS NOT ARRESTED. RECEIVED A RED CABIN ALTITUDE EICAS MESSAGE. PERFORMED MEMORY ITEM AND INITIATED DESCENT. REQUESTED ATC ASSISTANCE TO DESCEND AND VECTORS TO KPIE. AN EMERGENCY WAS DECLARED. FOUND AC DUCT TORN, CW SB680-21-08, R&R LT/RT DUCT ASSY.