I started the car and started to back it out of the garage but the acoustic warning persisted. I noticed that the brake peddle was not as firm as it used to be. I pumped the brake peddle and noticed that it was almost flat. I was able to back the car out of the garage but noticed during the process that the brake would not stop the car. We notice leaked brake fluid (or what looked like brake fluid) around the driver side tire.

I inspected the brake fluid reservoir and it was pretty much empty, if not empty.

I don't know what caused this brake failure apart from the fluid leakage.

A few error messages popped up and they include: Chassis stabilization: Drive moderately, Brake system: Stop carefully. Please call Roadside Assistance, Daytime Pedestrian Warning limited "Brake intervention not possible, but visual and acoustic warning are still given. Consult service center", Frontal Collision Warning System: "Malfunction. Brake intervention not available. Visual/acoustic warnings active. Consult service center"

The car was driven two days prior with any issues. If this failure had occurred on a highway or anywhere with high volume of traffic, it may have impacted others. BMW needs to look into this issue.

when stopping several times, the brakes seem to slip

There have been several in incidents where the brakes seem to slip when stopping. I believe the first time was during the summer of 2016. I was probably near 2800-3000 miles when I first noticed it. Luckily, I began stopping in time. I had to press on the brake a couple of times and fortunately it did stop. I wasn't sure if it was just me or something I had done wrong. This is a new BMW X3 purchased in November of 2015. It only had 10 miles on it when I drove it off the lot. I unfortunately did not mention this issue when I took it to its first service because I was hoping they would mention it after a thorough check. They did not. About a month or so after its first service, it happened again. Since the first time, I am very aware of stopping in time. This is very frightening. It doesn't happen every time I stop. I have been thinking that I need to have it checked, but not sure if the dealership would be honest.