Brakes suddenly stopped working?

Hello,

I took my husband’s car to take the kids to practice and after pulling out of the drive way, I pressed the brake so I could slightly readjust the seat. While my foot was on the brake pedal the brake pedal seemed to release suddenly and the pedal moved all the way down. Thought it was odd, so I drove a little further down our street and pressed the brake pedal again. While the car slowed down some, it definitely didn’t stop as fast as it normally would. So, I carefully turned around a pulled back into my driveway to call my husband. While my husband came outside, I pressed the brake pedal again a couple times and could hear air every time I pressed down (sounded like an air pump). When my husband got in the car, I walked around to the passenger side and noticed a puddle of fluid leaking out. My husband said he suspected it was brake fluid. Shortly after, he turned the car off and pressed the brake pedal and we could hear air hissing from the outside of the car and also on the passenger side. Upon turning the car back on, a light in his car came on to indicate that the brake fluid was low. I assume it’s not safe to drive the car to the shop, but any ideas as to what just happened?