New peace deal, but 'state of terror' spreads in Damascus

• Hillary Clinton praises a new international deal even as she admits it might fail
• 2,386 people were killed across Syria in June, opposition activists say
• Opposition members slam the idea that regime members could be part of the transition

(CNN) -- After world leaders heralded a new plan over the weekend to end the crisis in Syria, the agreement between typically sparring countries netted both optimism and doubt.

But on the ground, violence reigned once again early Monday as "a state of terror" spread in suburban Damascus, opposition activists said.

Fresh mortar shelling fell near an elementary school in Madyara, the opposition Local Coordination Committees of Syria said.

The latest international plan for Syria, backed by Russia and China as well as the West, calls for a transitional government as a step toward ending 16 months of daily bloodshed. Unlike many Western countries, Russia and China have not explicitly called for Syrian President Bashar al-Assad to step down.

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But U.S. Secretary of State Hillary Clinton conceded that the plan, forged in Geneva on Saturday, might not work.

"There is no guarantee that we are going to be successful. I just hate to say that," Clinton told CNN.

But she expressed optimism that the new agreement would help ease al-Assad out of power, saying the Syrian president and his inner circle would be excluded from any transitional government.

According to the agreement, the transitional government "could include members of the present government and the opposition and other groups and shall be formed on the basis of mutual consent."

Both sides have to agree on the membership of the interim body, and Clinton said there was "no way anyone in the opposition would ever consent to Assad or his inside regime cronies with blood on their hands being on any transitional governing body."

"Assad will not be part of it," she said in an interview late Saturday in Geneva, Switzerland, after the deal was hammered out.

But opposition activists slammed the agreement, saying it left open the possibility that al-Assad would remain in power.

"The new agreement provides vague language which is open to interpretation," the opposition Local Coordination Committees of Syria said in a statement Sunday. "This provides yet another opportunity for the regime's thugs to play their favorite game in utilizing time in order to stop the popular Syrian Revolution and extinguish it with violence and massacres across Syria."

A spokesman for the Syrian National Council, a prominent political opposition group, similarly slammed the agreement.

"We are afraid that the decision of the Geneva convention might give signs and gestures to the Syrian regime that it is acceptable and a legitimate cover to continue killing the people, and committing more massacres," Muhammad Farmini told CNN. "This gives the regime a permit to continue killing and spilling more Syrian blood."

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Clinton said the Russians, who have long been al-Assad's most steadfast supporters, had finally decided to back a transition away from his rule.

"They have committed to trying," she said. "But they also admitted that they may or may not have enough leverage to convince not just one man, but a family and a regime that their time is over."

Russia, widely viewed as a key ally to the Syrian regime, said the agreement should not be interpreted as outside powers imposing a transitional government on the Syrians. That process must come from inside Syria, Russian Foreign Minister Sergey Lavrov said.

Clinton said the U.N. Security Council should endorse the plan, thus allowing the possibility of sanctions against Syria if the requirements aren't met.

But for Syrians living amid the violence, the reports of carnage never stop.

The group said 69 people were killed across the country on Sunday.

June was a particularly gruesome month, with 2,386 people killed, the group said.

More than 14,000 people have been killed since the conflict began in March 2011; half of them were slaughtered in the past four months, the LCC said. The United Nations puts the death toll at more than 10,000.

CNN's Jill Dougherty and Holly Yan contributed to this report.