Updated

Egyptian authorities detained more than 60 people associated with the Muslim Brotherhood in less than 24 hours, including relatives of the group's leaders, officials said Wednesday.

The crackdown on the group, from which ousted President Mohammed Morsi hails, started shortly after the July 3 coup. It intensified this month after security forces cleared out two of the group's sit-ins, killing hundreds and sparking unrest that killed more than 1,000 people in a few days. The Interior Ministry says more than 100 policemen and soldiers have also been killed since mid-August.

The local media, in close step with the new leadership after Morsi, repeatedly describe the actions of the Brotherhood and its supporters as acts of terrorism. Many have been charged with inciting violence. Security forces have arrested much the Brotherhood's senior and midlevel leadership, while others remain in hiding.

Widening its campaign, police have started going after members' relatives, including the son of Khairat el-Shater, a Brotherhood deputy and financier charged in relation to the killings of protesters outside the group's headquarters in June. A U.S. citizen, the son of a fugitive Brotherhood figure, was also detained this week.

It was not immediately clear why police detained el-Shater's 23-year-old son. Officials only said Wednesday that police had arrested Saad el-Shater and that he had threatened to release documents allegedly showing ties between his father and U.S. President Barack Obama. Officials did not elaborate.

The brother-in-law of fugitive Brotherhood figurehead Mohammed el-Beltagy also was arrested in the latest sweep on charges he incited violent protests aimed at toppling the military-backed government that took over after Morsi. Police officials said Saeed Zaki Eissa and two others known to be affiliated with the Brotherhood were detained in Egypt's second largest city of Alexandria after prosecutors ordered their arrest.

All officials spoke on condition of anonymity as they were not authorized to speak to the media.

The security clampdown appears to have weakened the Brotherhood-led protests, which have been much smaller across the country this past week. The group is calling for mass protests Friday and urging its followers to take part in civil disobedience.

A statement by military spokesman Col. Ahmed Ali on Wednesday said two protesters were shot dead during a march of about 500 people against Morsi's ouster in the province of Bani Sueif. The spokesman alleged that the marchers had attacked a security patrol belonging to the military, prompting soldiers fire gunshots "in the air" to disperse the crowd late Tuesday.

The Brotherhood was once the most popular political party in the country, sweeping Egypt's elections. But the group quickly lost support during Morsi's year in office. Millions of people protested for Morsi's ouster, bringing the country to a standstill just days before the military toppled him.

Morsi's critics accused him and his Brotherhood supporters of harming the country with divisive policies and sidelining other groups in an attempt to grab power. The group says the coup was orchestrated by officials from the regime of autocrat Hosni Mubarak, who was deposed after a 2011 uprising.