Thoughts on what would cause this? We heard water come down and now it is coming out of the vent in our fireplace. It's raining pretty good here so my assumption is the fireplace cap on the roof is pooling water and water is coming in?

Water coming down your chimney somehow. Cap leaking or blown off.

Agree with cap - if not then

Roof flashing/decking/cricket

Even brick sealer (if any) or flue

Can you snap a pic from the ground of your chimney setup?

Jason_InfinityRoofer said:

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Can you snap a pic from the ground of your chimney setup?

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I didn't get home prior to the sun going down but I will try to snap one in the morning.

Well, crap. That could be leaking anywhere.

It could be the siding, maybe a crack, but not likely. It could be the cap, as others said, or it could be the flashing on the uphill back slope side of the chimney where it hits the roof. I don't know if it has a cricket but if not, that's a likely candidate.

This all can be leak tested with a water hose. Start low and work towards the top. Give it adequate water and adequate time to show up inside. Once it does, you'll know the area to focus on.

I fought something like this on my chimney for a year. Turned out it was a void in the masonry and the builder did not flash and wrap the inside correctly. A dab of caulking and it was sealed.

In other words, it's probably simple and if I had to guess based on the photo, I'm going to guess aged and failed caulking where the flue/pipe comes through the metal cap on top.