Expressjet E135 near Denver on May 4th 2014, loss of cabin pressure

An Expressjet Embraer ERJ-135 on behalf of United, registration N11127 performing flight EV-6184/UA-6184 from Madison,WI to Denver,CO (USA), stopped the climb out of Madison at FL240 and continued at that flight level until about 320nm northeast of Denver, then performed an emergency descent to 10,000 feet due to the loss of cabin pressure. The aircraft continued to Denver for a safe landing about one hour later.

A passenger reported the aircraft was about half way into the flight when the passenger oxygen masks were released and the aircraft performed an emergency descent.