The rulings by the Cairo Criminal Court are preliminary and will be referred to the chief Islamic legal authority, the Grand Mufti, for a non-binding opinion, as required by Egyptian law.
The other suspects on trial, out of a total of 68, have yet to receive their judgements.
A final verdict on all defendants is scheduled for October 10.
The accused are charged with murder, sabotage and unlicensed possession of weapons.
The case dates back to August 2013 when angry Islamists attacked a police station in the Cairo southern suburb of Helwan with petrol bombs and firearms. Later they set the building on fire.
Three police officers and three civilians were killed in the assault. Nineteen others were injured.
The attack took place after security forces forcibly cleared two Islamist sit-ins in Cairo. Hundreds were killed in the crackdown, according to rights groups.
The sit-ins had been staged in protest against the army's 2013 overthrow of Islamist president Mohammed Mursi following street demonstrations against his divisive rule. Mursi was Egypt's first democratically elected president.
Egyptian courts have issued heavy-handed sentences against followers of Mursi's Muslim Brotherhood in different cases since his toppling.
The rulings by the Cairo Criminal Court are preliminary and will be referred to the Grand Mufti, for a non-binding opinion.
An Egyptian court on Saturday sentenced eight suspected Islamists to death on charges of carrying out a deadly attack on a police station in Cairo nearly four years ago.
