As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE CLIMBING THROUGH FL380, THE CABIN ALTITUDE HORN & MASTER WARNING ANNUNCIATION WERE TRIGGERED. THE CREW CONFIRMED THAT THE WARNING WAS VALID, AS THE CABIN ALTITUDE WAS INDICATING ROUGHLY 10 TO 11,000 FEET & THE CABIN VSI INDICATED A RAPID CLIMB. THE CREW ELECTED TO DESCEND AT THAT TIME. AN EMER WAS DECLARED SUCH THAT ATC WOULD AUTHORIZE A DESCENT TO AN ACCEPTABLE ALTITUDE.