chicken just died

[btxchick]

I live in central Texas and it's, of course, super hot this year. I am a first time chicken person and have been keeping close watch on them throughout the summer and they have been tolerating the 100+ heat very well. Me and my boyfriend check on them frequently while we are home checking for eggs and assuring that they have water. Today my boyfriend went outside and my barred rock was laying in her usual spot, 1.5 hours later I went outside to have my cousin feed them treats and found her laying on her side, eyes open but barely responsive and trembling. I picked her up to bring her into the A/C to cool off but she died in my arms on the way to the house. She had layed the egg and come out of the coop and layed in the run.
Is this from the heat? It is the only thing I can think of, I have a very healthy and lively flock and haven't had a problem with them outside. I even place frozen water bottles out there ( a suggestion I got from the forum!) to help keep them cool.
I'm very sad about this loss, naturally, I raised them from chicks and just wish that there was something I could have done. I mean it was only 1.5 hours since they were checked on and seemed fine, this scares me! The coop and their whole fenced in area is very shaded, with a breeze and the coop itself is ventilated so the air doesn't get stagnant or too warm in there. The coop is elevated and the run is below that but I open it up and they have free range of a large fenced in area, all shaded.
What else can I do to prevent this? A fan maybe? A mister? Any suggestions are helpful.

 

[Pebbles]

I'm so sorry for your loss. I live in Arizona so I know hot weather for months on end. Every year the first week of really hot weather-over 100 degees- I always loose a hen or two. Mine,like yours, have shade and plenty of cool water, in a breezy location. Sometimes we do all we can but during extreme heat or cold if there is a slight illness or weakness in their physical make-up we loose them. It is always such a shock isn't it. We stress over them and tend to them and protect them and we feel like such failures when we loose one. Know that you are doing your best for your girls and the one you lost had a good life under your loving care.

 

[Jesseschickens]

Im sooooo so sorry i remeber when i lost my first hen back in march. but sadly we have no idea how she died though i remeber i couldnt stop crying for a long time. Right now i have a hen that "flew the coop" and im really worried

 

[texastinsel]

I am so sad to hear of your loss....be strong....