Anti-government protesters march in Idlib, Syria, on Friday, as more people were reported killed.

Story highlights

NEW: Syrian opposition say they have formed breakaway government council

NEW: Many details have yet to emerge on the new Syrian National Council.

NEW: Activists say eight people die in clashes and random gunfire on Saturday

Syrian ambassador summoned over attack against U.S. ambassador, an official says

CNN  — 

Syrian opposition groups said Saturday that they have formed a breakaway government, but many details were yet to emerge.

The Local Coordination Committees, which organizes and documents protests against the Syrian regime, said 188 seats have so far been assigned to the council, but it may be 24 hours before the announcement of a presidential body.

Groups including the Muslim Brotherhood of Syria, the Revolution Forces, the Public Council for Revolution Forces and the Superior Council of the Revolution have all joined the LCC in the opposition government, the LCC said Saturday.

The groups are trying to create a Syrian National Council aimed at toppling the regime of President Bashar al-Assad.

Syria has been locked in a violent months-long uprising that has seen security forces clash with anti-government protesters calling for free elections and the end of al-Assad’s rule.

Activists said at least eight people died in protests and random shootings on Saturday, a day after the government said 13 security forces and three civilians died in clashes and an opposition group said 23 people, mostly civilians, died in the fighting.

Activists also said women marched near the presidential palace in Damascus on Saturday, demanding the fall of the regime, the release of detainees and the lifting of blockades throughout the country.

CNN is unable to independently confirm the claims.

Al-Assad, who has characterized the protesters as “armed gangs,” has insisted his security forces are battling terrorists intent on targeting civilians and fomenting unrest.

The United States, the European Union and a number of Arab countries have called an al-Assad to end the crackdown and step down.

Tensions between the United States and Syria escalated after the Syrian ambassador to the U.S. was called Friday to the State Department over an attempted attack a day earlier in Damascus on American Ambassador Robert Ford, spokeswoman Victoria Nuland told reporters.

“The ambassador was reminded that Ambassador Ford is the personal representative of the president, and an attack on Ford is an attack on the United States,” Nuland said.

About 100 pro-government protesters tried to storm a meeting between Ford and opposition leader Hassan Abdelazim, trapping Ford and others for more than an hour. Later, his convoy was attacked.

The al-Assad regime had earlier accused Washington of inciting “armed groups” into violence against its security forces.

Nuland said Ambassador Imad Mustapha was asked to compensate the United States for damage to the vehicles.

In a Facebook post Friday, Ford said he respected “peaceful protest” – including by pro-government factions to express their opposition to him and U.S. policy – but insisted that Thursday’s incident was “not peaceful.”

He described demonstrators wielding iron bars; throwing tomatoes, eggs and concrete blocks; attacking embassy vehicles; and trying to break into Azim’s office.

“Americans understand that we are seeing the ugly side of the Syrian regime, which uses brutal force, repression and intimidation to stay in power,” Ford wrote.

“We deeply feel for the Syrian families that are enduring the violence, killings and torture and pain. We hope that Syrians find solutions to the crisis soon, but we strongly doubt that the regime’s terrorizing the population will end the crisis.”

Syrian state-run media, citing the Foreign Ministry, reported Friday that “necessary measures” had been taken to protect Ford.

Taking a page from the success of Libya’s National Transitional Council, Syrian opposition groups meeting in Istanbul worked together to bring the various groups under one opposition umbrella.

Among those expected to be represented by the National Council are the Muslim Brotherhood, the Assyrian Organization and the General Authority of the Syrian Revolution, the LCC said.

The LCC does not identify its membership out of a fear of reprisals by al-Assad’s security forces. CNN cannot independently verify the claims of the group because the Syrian government has denied international journalists access to the country.

The meeting concluded the same day news broke that prominent anti-government activist Marwa al-Ghemyan was detained Friday by Syrian security forces at the Damascus airport.

Al-Ghemyan was detained as she was preparing to depart the capital and taken to a military security building, the London-based Syrian Observatory for Human Rights said in a statement. The opposition group, which documents Syria’s anti-government movement, did not say how it confirmed her detention.

Al-Ghemyan was previously detained by Syrian forces on March 4 and released on March 21, the group said.

CNN’s Elise Labott, Hamdi Alkhshali and Chelsea J. Carter contributed to this report.