Maybe a disgruntled employee. As mentioned.. we don't really know yet. We just see a huge fire giving off huge plumes of black smoke, maybe building material, maybe oil, could be a lot of things. Looks nasty. Mentioned several times it looks like a 9-11 type of fire .
As to the bolded question.. many companies have the policy, pull fire alarm, call fire department, evacuate building, and then, yes, may have the clause, do not attempt to put fire out yourself.
They probably have this in place for if the employee somehow gets injured trying to put out the fire.
Some companies say, only attempt to do so if you feel comfortable. There ARE fire extinguishers on every support column, other places.. I am one of the only ones that will not put things in front of fire extinguishers.
Let's see what develops here.