The Saudi Health Ministry reported 21 dead in the first attack claimed by the militant group in the country.
The campaign against such entities is “the worst attack on civil society” in the country’s history, an activist says.
Aid agencies say food, gas and medicine are at dangerously low levels.
The verdict, which can be appealed, marks a stunning blow to the pro-democracy revolt of 2011.
A five-day humanitarian halt to the fighting is supposed to allow supplies to enter the war-ravaged country.
A Saudi-led coalition continued air raids in Sanaa; rebels claim to have downed a Saudi-allied Moroccan jet.
Scores of people were killed in the country Wednesday as rebels pushed further into the port city of Aden.
The verdict is the first against the ousted Islamist leader since he was detained nearly two years ago.
The corpses offer some of the first concrete evidence about a terrible massacre of Shiite soldiers in Tikrit.
Russian President Vladimir Putin landed in Egypt on Monday, calling on fellow strongman and Egyptian President Abdel Fattah El-Sissi