Four people including an Egyptian woman journalist were killed in Cairo Friday as police clashed with Islamists protesting against ex-army chief Abdel Fattah al-Sisi’s presidency bid, a security official said.

Four people including an Egyptian woman journalist were killed in Cairo Friday as police clashed with Islamists protesting against ex-army chief Abdel Fattah al-Sisi's presidency bid, a security official said.

The violence erupted in a deeply polarized Egypt as supporters of deposed president Mohammad Mursi took to the streets of Cairo, Alexandria and other cities to vent their anger at Sisi who overthrew the Islamist nine months ago.

Mayada Ashraf, who worked for the privately owned Al-Dustour newspaper, was shot in the head while covering clashes in the northern neighbourhood of Ein Shams, the official said, adding that three more people were killed in the same violence and 10 wounded.

Four people were also wounded in clashes in the northern province of Damietta, health ministry official Khaled al-Khatib told AFP.

In Cairo's eastern neighborhood of Madinat Nasr, students from Al-Azhar Islamic university hurled Molotov cocktails and stones at riot police who fired tear gas to disperse them, security officials said.

Underlining Egypt's deep polarisation, clashes also erupted between Mursi supporters and his opponents in the northern Cairo districts of Ein Shams and Matareya, the officials said.

Ten Mursi supporters were arrested in clashes with security forces in Damietta province, and 28 were arrested in the southern Minya province for carrying leaflets hostile to the military and the police, they added.

Demonstrators in the southern Cairo working class district of Helwan and in Fayum province, southwest of the capital, fired birdshot and police responded with tear gas, state news agency MENA reported.

Supporters of the widely popular presidential hopeful, who toppled Mursi after massive street protests against his turbulent one-year rule, also demonstrated to celebrate his candidacy.

Carrying Egyptian flags and portraits of Sisi, dozens marched in Alexandria and scores gathered in Cairo's iconic Tahrir Square, symbol of the 2011 uprising that toppled veteran president Hosni Mubarak.

Sisi, who was also defense minister and deputy prime minister, announced his resignation on Wednesday to enable him to stand in the election.

His candidacy is likely to further inflame Islamist protesters and worry secular activists who fear a return to rule by the military and the strong-arm tactics of the Mubarak era.

Sisi faces no serious competition in his bid for the presidency and is widely seen as the only leader able to restore order after more than three years of turmoil.