Oil and Coolant Leak, Serpentine Belt fell off

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Having a pretty unfortunate issue with my 08 Hatchback. I had my first partial synthetic oil change last service, about 6k miles ago. Car has 170k miles. I usually only do conventional and will be sticking with conventional for now on. I was told I could go 7k miles on this oil change. I was on the way to get an oil change, after my engine was making some weird noises like it was low on oil. When I get to the (drive-thru) oil change shop, they let me know there is oil and coolant leaking all over the right side of the engine compartment, and that my serpentine belt had fallen off.

I drove 5min to my mechanic (wouldn't go any further without towing it) and he is going to look at it tomorrow. Could this possibly be caused by waiting too long for an oil change, different kind of oil being used, or anything else? Could the leaks themself be caused simply by the serpentine belt failing (it did not snap, only slipped off; it was covered in oil and is about due to be replaced)? Also the coolant temperature light came on for the first time in that 5min drive to where the car is now. I am not mechanically inclined, but any idea on advice I should give to my mechanic?

Thanks