I'm making a video collage of photos from the internet of the California wildfires to ask for people's donations for the first responders. Will I run afoul with copyright laws in doing this, or will this be ok under a 'fair use' case, as I am not looking to profit, but rather collect donations for charity.
Collecting donations is profiting. Merely because those profits will be used in order to help someone/thing it doesn't change the fact that usage of the images would be benefiting an organization.
There's no such thing as "altruistic usage" which circumvent copyright infringements.
"Profit" in terms of unauthorized image use equates to any use which provides value. "Fair Use" refers to usage where nothing is directly gained from the use.
It certainly sounds to me as though the usage you describe would be unauthorized use and an infringement.
Charities, non-profits, and/or not-for profit organizations do not get "free reign" to use anything merely due to the nature of their business. They are bound to copyright laws the same as any other organization.