The court also handed 114 people sentences ranging from 15 years to life (25 years) and ordered a juvenile jailed for 10 years, they said.
A further 21 defendants were acquitted.
On August 14, 2013, a month after the army overthrew Morsi, security forces forcibly dispersed two pro-Morsi protest camps in Cairo in an operation that killed more than 700 people.
Hours later, a furious crowd attacked a police station in the Cairo suburb of Kerdassa, where 13 policemen were killed.
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All the defendants were present in court during the ruling, which can still be appealed.
The death sentences have already been approved by the mufti, Egypt's official interpreter of Islamic law, whose opinion is legally required but not binding.
This is the second trial over the same case.
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The court of cassation called for a retrial after a lower court sentenced to death 183 Islamists over the killings.
Egyptian courts have issued hundreds of death sentences against Morsi supporters since his overthrow, but many have appealed and won new trials.
Morsi and other top Muslim Brotherhood figures have also faced trial.
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