UPDATE: WATER HAS STOPPED. It is, indeed, a water line break. River Rd. Utility talked me through shutting off the water at the meter. It was so strange that it was coming in through the stovepipe, though. Thanks to everyone who responded!!!
Any roofers, or maybe chimney people out there? Or a contractor, I suppose! I believe the seal around our stovepipe coming out of the roof was crap to begin with or was compromised by the snow and ice. I have water spewing out of the bend in the stovepipe in the basement. Went up on the roof to clear away as much snow as I could but it hasn't helped any. I'm emptying buckets every 3-5 minutes and will likely be up all night doing that. Need help sealing it up tomorrow if someone is available!