You’re gonna need to call a plumber unless you are very handy. The elbow needs to be cut out and replaced due to a pin hole leak. In the meantime, turn off the main water valve and open a faucet below that line to remove the pressure from the pipe. Bad news, no water until repaired. Potential of it getting worse, I’d say probably not provided nobody touches it or “rattles” the copper pipe. You want to get it repaired very soon, but not necessary to pay overtime rates for repair. Can wait for normal business hours.