First off your engine stopped running, that's why you got no response from the gas pedal. Brakes and steering are power meaning the engine must be running for them to operate properly. DON'T PANIC, you still have steering just not assisted. The brakes might sort of work for a application or 2, BUT that's what the parking brake is for USE TO BE CALLED EMERGENCY BRAKE. It's very nice that we have a parking brake level just hold the button in and pull up and down to adjust your braking amount required.
Something made your engine just stop without warning. It happens from time to time. Check the things the other members have mentioned. Glad you're OK and nobody was hurt.
Cheers