At least 17 killed as competing rallies clash in Cairo and across Egypt

At least 17 people were killed and hundreds injured in violent clashes across Egypt as hundreds of thousands gathered to swell rival protest camps in support or opposition of the military coup that ousted former president Mohamed Morsi.

Rival protesters in Cairo, Alexandria and other cities have been locked in a struggle over the future of the Arab world’s most populous country.

Protests turned deadly in the Cairo neighborhood of Nasr City, where at least 10 were killed in the early hours of Saturday (late Friday night EST) in a gun attack on supporters of ousted president Mohammed Morsi.

Al Jazeera's Jamal Elshayyal, reporting from Nasr City, said that there had been a stream of injured people being taken to a field hospital in the city. Many were suffering from gunshot wounds and the effects of tear gas.

A special correspondent for Al Jazeera, reporting from the field hospital in Nasr, described the scene:

"I am standing in a room 20 ft square, there are 20 to 30 beds lined up and every two to three minutes someone is brought through the door covered in blood," he said. 

"There is evidence of live fire, puncture wounds. There is blood all over the place. It's chaotic. These are rudimentary facilities ... no means to deal with bullet wounds."

The shootings took place after police clashed with pro-Morsi protesters who had tried to block the October 6 Bridge in Nasr City, shortly after the Interior Minister Mohamed Ibrahim said that the Muslim Brotherhood protests in the city would be cleared "soon and in a legal manner".

In Alexandria, Egypt's second largest city, seven people were reported killed and 70 injured in clashes between rival demonstrations. Most of the cases were a result of bird shot and wounds from sharp objects all over the body, according to the head of the ambulance authority.

Security forces had also moved in on an anti-coup sit-in at Qaed Ibrahim mosque in the city. At least 180 people have been killed this month alone in rallies that have turned violent.

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Unknown assailants with rocket-propelled grenades also attacked two checkpoints and a police station in northern Sinai on Friday evening, police said.  

The attack began at sundown as people were breaking their fast, a police source told Al Jazeera. The source said residents in the area were warned to stay indoors and that many took shelter at local mosques. The number of people injured in the incident is still unclear.

Egypt has been convulsed by violence for the past three weeks, with some 200 people killed since Morsi's ouster in a military coup on July 3, Agence France Presse reported. Many of the deaths occurred in clashes between Morsi’s Islamist supporters and his opponents.

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Tensions were further inflamed Friday after a judge ordered the detention of Morsi over his alleged contacts with Hamas during his 2011 escape from prison.

Earlier, Egyptian health ministry sources told Al Jazeera that 24 people were injured in Cairo and Damietta, which is about 115 miles from the capital, in clashes.

Police forces also used tear gas at a protest near Qaed Ibrahim Mosque in Alexandria. 

The protests came in response to a call by military chief Gen. Abdel-Fatah el-Sissi earlier in the week for a show of popular support for his anticipated crackdown on Morsi's supporters and those loyal to the ousted leader who have been attacking security forces. The Muslim Brotherhood, the country's leading Islamist group from which Morsi draws support, also called for mass protests on Friday.

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As the rival rallies and serious charges against Morsi raised the specter of violence between the two camps on Friday, the military, police and army deployed tens of thousands of members across the country to protect protesters.

Earlier Friday a judge ordered Morsi to be detained for 15 days pending investigations on charges of spying for Hamas and breaking into prisons during the 18 day revolt that toppled former president Hosni Mubarak in February 2011, state prosecution officials confirmed to Al Jazeera.

While the move against Morsi is the first official charge against the former President since the coup, he has been held incommunicado by military authorities since July 3.

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Senior Muslim Brotherhood leader Essam El-Erian condemned the reported arrest warrant against Morsi.

"This is an invalid accusation. They want to stir discord in the society and to instigate violence amongst the demonstrators. But we insist that our million-person march, the Friday of Discernment, is a peaceful protest, and we will not interfere with the other protesters [their rivals] -- It is the right of every Egyptian to express their point of view peacefully and without violence," he told Reuters.

Morsi’s detention could be extended as the inquiry continues, Egypt’s state news agenecy MENA reported. The news agency also indicated that Morsi has already been interrogated.

The case against Morsi is rooted in the mass jailbreak of more than 30 Muslim Brotherhood leaders from a prison northwest of Cairo during the 2011 popular uprising that toppled Morsi's predecessor, autocrat Hosni Mubarak. There have been many reports in the Egyptian media that the Brotherhood collaborated with Hamas, the Palestinian resistance and political organization which is a longtime ally of the Brotherhood.

Muslim Brotherhood officials have said they were aided by local residents in breaking out of prison, not foreigners. However, a court in the Suez Canal city of Ismailia has heard testimonies from prison officials and intelligence officers strongly indicating that Morsi and his Brotherhood colleagues were freed when gunmen led by Hamas operatives stormed the Wadi el-Natroun prison.

Hamas has consistently denied any involvement. On Friday a spokesman for the militant group, Sami Abu Zuhri, condemned Morsi's detention order. "The Egyptian decision is an attempt to drag Hamas into the Egyptian conflict," he said. "We call on the Arab League to bear its responsibility in facing the incitement against Hamas."

Al Jazeera and wire services