I was driving to work and noticed white smoke coming from under the hood. I noticed my low coolant light came on and I drove to my destination, then shut off the car. I have not done anything as of yet.
As raydowe says in their comment the white "smoke" you saw is almost certainly coolant burning/boiling off.
This could be from a leak in the system causing coolant to hit hot parts of the engine bay (such as the exhaust manifold) or it could be that the engine has overheated and the coolant has boiled over and escaped via the expansion tank. From the details we have it's impossible to know which. If I recall correctly the 2.8 V6 9-3's of that era had quite a common problem with the coolant tank itself cracking which would certainly fit with the symptoms you describe but I'm just speculating.
Either way I would not be driving the car any further - driving with an overheating engine can result in significant (and expensive) damage to the engine and even if this morning's drama were just it losing the coolant and not quite reaching overheating stages yet it's almost inevitable if you try and drive it without a suitable amount of coolant in the system.