CAIRO -- Anti-government protesters fought street battles with police in Cairo and other cities Sunday, the fourth anniversary of the country's 2011 uprising, as clashes left at least 15 people dead and dozens injured. Another two people died when an explosive device they were planting under a high-voltage tower in the Nile Delta exploded prematurely, according to security officials.
Most of the deaths took place in Cairo's eastern Matariyah district -- an Islamist stronghold where police used tear gas and birdshot to disperse supporters of the outlawed Muslim Brotherhood group armed with firebombs and rocks. At least nine protesters and one police conscript were killed in the clashes there, officials said.
Two other protesters and two policemen were killed elsewhere in Cairo on Sunday and one in the Mediterranean port city of Alexandria, said the officials, who spoke on condition of anonymity because they were not authorized to speak to the media.
The violence underscored the continued turmoil roiling the Arab world's most populous nation four years after the 18-day uprising that toppled autocrat Hosni Mubarak.
It also casts a light on the multitude of challenges faced by President Abdel-Fattah el-Sissi, who since taking office in June has been struggling to revive the economy, battle an Islamist insurgency, and deal with dissent by both Islamists loyal to Mohammed Morsi -- the elected president he ousted in 2013 -- and the secular and liberal groups behind the 2011 uprising.
Both camps are targeted in crackdowns by el-Sissi's government but show no sign of being able to overcome mutual distrust and join forces. A career army officer, el-Sissi says his priorities are fixing the economy and battling the insurgency. He has resisted growing calls for change, while influential media loyal to him have begun regularly maligning the 2011 revolution and its activists.
The Health Ministry said 37 people were injured in Sunday's clashes, and the Interior Ministry, which is in charge of police, said a total of 134 protesters were arrested nationwide.
By early evening, debris covered the site of the Matariyah clashes and a cloud of tear gas hung over the area. Video shot there earlier in the day showed pedestrians and communal taxis caught in the crossfire between the two sides. The video is consistent with Associated Press reporting on the clashes.
Cairo, a city of about 18 million people, appeared mostly deserted Sunday. Police sealed off the city's main squares, including Tahrir -- birthplace of the 2011 uprising -- and beefed up security at vital state installations.
In downtown Cairo, el-Sissi supporters clashed with mostly young critics of the general turned politician in pitched street battles. Police later used tear gas and birdshot to disperse the president's critics.
The protests and stepped-up security in Cairo and elsewhere came as activists mourned the death of a female protester shot Saturday in downtown Cairo while taking part in a gathering commemorating protesters killed in the 2011 revolt.
Activists blame police for the death of Shaimaa el-Sabagh, 32, a mother of one from Alexandria. The government says it is investigating the death.
Videos posted online show el-Sabagh, a member of the leftist Popular Alliance Party, with other protesters carrying placards and chanting.
In the videos, two masked, black-clad police officers point their rifles in her direction before gunshots ring out. The next frame has her on the ground. She is later shown being carried by a male protester as blood seeps out of her mouth. The videos are consistent with AP reporting on the shooting.
Chanting "down, down with military rule!" hundreds attended her funeral in Alexandria on Sunday.
The prominent Hisham Mubarak Law Center said in a Facebook post that five of el-Sabagh's fellow protesters who had given investigators their account of the death were charged with assaulting police and taking part in an illegal demonstration.
There was no immediate confirmation from authorities of the group's claim.
El-Sabagh's death is the second of a female protester in recent days. Islamist Sondos Reda was shot dead during a Friday protest in Alexandria. Activists also blame the police.
El-Sissi's government has shown zero tolerance for street protests since a law adopted in 2013 banned all demonstrations without prior permission.
Dozens of activists have been convicted and jailed for violating the law. A parallel crackdown is targeting Morsi supporters, with thousands from his Muslim Brotherhood group imprisoned or facing trial.
"You can only deal with terrorism when you have free people, not slaves," Elhami el-Mirghani, a senior official in el-Sabagh's political party, said during a news conference Sunday. "And this regime is the biggest creator of terrorism."
A Section on 01/26/2015