Regional Jet 700 ER/LR (CRJ700)
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed in Emergency Condition; Flight Crew Diverted
Aircraft
After leveling at cruise for a few [minutes]; got a Cabin Alt. caution msg. After getting some of the QRH done and starting down; got Cabin Alt. warning message. [Advised ATC] and diverted to ZZZ. The smell from the O2 canisters smelled like there may have been a fire. It took a few mins. to figure out it was just the O2 canisters making the smell. After landing had fire and rescue inspect aircraft. Taxied to the gate. Talked to [passengers] to let them know basically what happened. Asked if anyone needed help by paramedics on the airplane and all said no. So we let the [passengers] know that everyone would be [checked] out by paramedics in the gate area once they all deplaned. Everyone checked out ok is what I was told. Before leaving the gate in ZZZ1 had to get my O2 mask replaced because it would not test. Need to make sure every pilot knows how to pre-flight/check the O2 mask the correct way. Some [passengers] said they could not get their O2 mask to work. FA (Flight Attendant) tried to help and could not get O2 to come out [of] the [passenger's] mask. FWD FA O2 mask could not get O2 [to] come out. Even after being tested by [Maintenance] and the canisters got hot; it is not a sure way of telling that O2 came out of the mask or not. The auto 1st class PA did not work when the O2 mask deployed is what I was told by the FA's. [Cause of incident] appears [to be] the outflow valve opened.After an event there is way too many phone calls. Makes things way too confusing. Understand calling Dispatch and Maintenance. Had to answer so many question right off the bat from the company did not have time to finish the write ups and had to go back to finish. This brings another point to mind. If something comes out on [Company Document] lets say at midnight the pilot is responsible for the pages of info on their [flight]; lets say at 6 am. This is not realistic and needs to addressed. Need to give a minimum of 5 days for a pilot; mechanic; and/or FA to be able to understand the info NOT just checking a box. The pilots are responsible if they get a line check to have [Company Document] up to date or pulled off line. This is NOT safe.Always check your O2 mask before leaving the gate. Need to make sure every pilot knows how to preflight/ check the O2 mask the correct way.
Air Carrier Captain flying CRJ-701 aircraft reported inflight de-pressurization.