B737-800 flight crew reported loss of pressurization during descent.

Narrative

We had begun our initial descent on the STAR; and had leveled at FL270; when several minutes after reaching that level; the cabin altitude horn went off which drew our attention to the cabin altitude gauge; which had shown a rise in the cabin altitude to approximately 13000 ft. At this time; the Captain; in the pilot monitoring (PM) role had announced that we don our masks; execute the immediate action memory items; and run the QRC per FOM guidelines. Through guidance of the QRC; we derived at the conclusion that the cabin was uncontrollable; which segues us into the QRH. In this; it guided us to commence with the cabin altitude warning/rapid decompression/[priority] decent.[Priority handling was requested] with ATC which led to vectors of our filed route clearing terrain. Due to MSA; we could not safely attain 10000; due to the mountainous terrain. ATC vectored us on a Northeasterly heading to clear terrain as it descended towards the front range. ATC was asked to notify the company of our situation as we were task saturated keeping the aircraft on a safe trajectory; while managing the cabin depressurization and attempting to communicate with the flight attendants. We notified ATC that our intent was to recover in ZZZ and shared our critical info (SOB; fuel; DG). In the decent we were able to gain control of the cabin altitude and dial the cabin altitude back down below. 10000. There was a large issue in trying to communicate with the Flight Attendant (FA) due to the volume of the exhale function on the masks. This was far louder than the volume that voice modulation was taking place. It made it near impossible to hear the FAs and the comm radios alike.The PM addressed the passengers of the abnormality while I handled the aircraft and radios. Ultimately; we were given priority handling by ATC and flew the ILS XXL approach into ZZZ. We landed without further issue; and the Captain reached out to the chief pilot; Maintenance Control; and Dispatch per FOM protocol.