Sporadic skirmishes erupted in Egypt Thursday as police quashed attempts by supporters of ousted Islamist president Mohammed Morsi to stage rallies marking the first anniversary of a brutal Cairo crackdown.

On August 14, 2013, after then army chief and now President Abdel Fattah al-Sisi had removed Egypt’s first freely elected president, the security forces cracked down on thousands of Morsi supporters at protest camps in Rabaa al-Adawiya and Nahda squares, leaving hundreds of people dead.

The assault was “one of the largest killings of demonstrators in a single day in recent history,” the New York-based Human Rights Watch said in a report released ahead of Thursday’s anniversary.

In Rabaa al-Adawiya alone, at least 817 people were killed, it said, calling for top officials to be investigated for likely “crimes against humanity.”

Official estimates say more than 700 people were killed at the two squares on that day.

On Thursday, attempts by Morsi supporters to demonstrate were swiftly suppressed, reflecting their dwindling ability to stage protests amid a brutal crackdown that has left more than 1,400 people dead since Morsi’s ouster in July 2013.

The pro-Morsi Anti-Coup Alliance had called for nationwide rallies on Thursday under the slogan “We Demand Retribution.”

Seven people were injured in the Mediterranean city of Alexandria when police fired tear gas during clashes with pro-Morsi demonstrators in three neighborhoods, security officials said.

Similar incidents were reported in the Nile Delta province of Sharqiya and in the town of Kerdasa, southwest of Cairo.

Skirmishes were also reported in Cairo’s Matariya district, and protesters briefly blocked roads with burning tires in the capital’s Helwan and Maadi suburbs, and torched a police car in the Haram neighborhood.

Security officials reported 19 protesters arrested nationwide.

The authorities blamed the Muslim Brotherhood for “disturbing Egypt’s stability… after they failed to rally for protests.”

Security forces were deployed around Cairo’s main squares including Tahrir, Rabaa, Nahda and Giza to thwart any attempts by pro-Morsi groups to hold rallies.

Sisi overthrew Morsi after millions of people took to the streets demanding the Islamist’s resignation after just one year in office.

They accused him of monopolizing power and ruining an already dilapidated economy.

Sisi replaced Morsi as president after securing a landslide victory in May this year, becoming the country’s second democratically elected president.

In a separate incident on Thursday, gunmen on a motorbike shot dead a policeman in Cairo. The motive for his killing was unclear.