shifting issues with 96 blazer

I have a 96 blazer, and while driving it down the freeway (I had been on the road at least an hour) when all of a sudden it just started whining and then
I noticed the temp gage shoot up. The automatic transmission would not shift out of second. I had to drive it the 50 miles home going 25 in second gear. Any ideas?
Message posted via

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.