I have gotten this before - it is bad news. Based on your description it is bacterial wilt - I am almost sure.
The plants will only worsen and you're not going to get a crop so the only thing to do is remove the plants immediately and throw them in the trash (not the compost) - since I think having it in the compost could make you more likely to get it in the future.
Hopefully it has not spread to your other plants but unfortunately there is a good chance they have it too and are just earlier on in the process. Supposedly pumpkins take a little longer to show signs.
It comes from a bacteria that is spread by cucumber beatles. I have gotten it on my cucumbers before too.

Do some checking (and wait for more responses) before yanking them - but your description is exactly the description I gave to people 7 years ago - that distinctive bounce back when they get water and then worsening.
Check for squash bugs and eggs too.

Here is a link that might be useful: Some info

Here is another article on bacterial wilt.

I was told not to plant any squash or cucumbers in the garden for 5 years. I think I waited 3.5 years (the .5 year being a late planting of squash in mid-july) and so far I am 3 or 4 years clean.
It really sucked not having fresh squash though.

Here is a link that might be useful: Cornell article on pumpkin wilt