bad start this morning in Cairo

Many people are reporting a massacre of pro-Morsi protestors during dawn prayers (at Republican Guard Headquarters where Morsi is apparently being detained). Others are saying the Brotherhood fired first, but the vast majority of reports are saying otherwise.

@Alastair_Beach on Twitter (from the UK Independent) is giving the most detailed tweets I can find so far.

The last figure I saw was 20 dead and over 300 injured.