The state of the heavy firefighting aircraft fleet is beyond reprehensible. 10 years ago there were nearly 40 heavy aircraft in service. Due to their age and poor safety record, most of that has been retired. At the start of the fire season this year, the US had 11 capable heavy air firefighting planes, but has already lost two (one crashed into a mountain when it veered off course from its lead plane in Utah and the other in a landing incident in Nevada). What is left is largely P2V aircraft that are 50+ years old. The military has capable aircraft, but they are not allowed as part of the on-call services available to the forest service and others, unless a certain threshold of criteria are met, which has not as of yet.
The 747 supertanker is out of business as of this year. It is currently parked at Marana, AZ (which was its home base as well) without engines. Its operating costs were too high and nobody was interested in paying the bills.
At least one of the DC-10 is working a fire in New Mexico.
The Forest Service has been studying what to do with the fleet for years and keeps kicking the can down the road. The latest plan didn't add any new airframes to the fleet until 2020 at the earliest. The wildfires this year cut a bunch of red tape as indicated in the link above.
A sad, sad state of of affairs.