Bombings claimed by the Islamic State group in the Syrian cities of Damascus and Homs killed nearly 130 people on Sunday, highlighting the threat posed by the extremists as the country's warring factions fight for the northern city of Aleppo and world powers chase an elusive cease-fire.

The blasts came as Secretary of State John Kerry said that a "provisional agreement" has been reached on a cessation of hostilities that could begin in the next few days. But he acknowledged that it's not finalized and all parties might not automatically comply.

A series of blasts ripped through the Sayyida Zeinab suburb of Damascus, killing at least 83 people and wounding more than 170, the official SANA news agency said. The Britain-based Syrian Observatory for Human Rights, which relies on local Syrian activists, said the blasts killed 62. SANA said the bombs went off near schools during the afternoon rush hour.

The neighborhood is home to one of Shiite Islam's holiest shrines, which his heavily guarded by Lebanon's Hezbollah movement and other Shiite militiamen from Iraq and elsewhere. Hezbollah's Al-Manar TV said the blasts were caused by a car bomb and two suicide bombers.

The bombings in the central city of Homs killed at least 46 people and wounded dozens, according to Syria's Foreign Ministry. The Observatory said 57 people, including 11 women, were killed by two car bombs set off in a mostly Alawite neighborhood. Syrian President Bashar Assad hails from the Alawite minority, an offshoot of Shiite Islam.

Syrian TV footage from Homs showed streets filled with debris and mangled cars, and the charred body of a man being taken away on a stretcher. Footage from Sayyida Zeinab showing people running in narrow streets as others carried the wounded, including several children. "He's alive, he's alive," a man shouted as he tried to administer CPR to an unconscious man. The TV later called on citizens to donate blood.

The Islamic State group claimed both attacks. The extremists are dug in on the outskirts of the two cities and have repeatedly targeted Shiites, who they view as apostates deserving of death.

The deadly blasts may strengthen the government's argument that it should press ahead with a major offensive in the north of the country, where troops backed by Russian airstrikes are close to sealing off Aleppo, once Syria's largest city and commercial hub. Syrian insurgents, including Western-backed rebels, seized several neighborhoods in 2012.

The heavy fighting near Aleppo led to collapse of peace talks earlier this month. World powers later agreed on a "cessation of hostilities" to begin within a week, but the deadline passed with no letup in the fighting.

Kerry has since reached out to his Russian counterpart, and during a visit to Jordan on Sunday, said they had struck a "provisional agreement" and must now reach out to the opposing sides on the ground. Russia is a key ally of Assad's government, while the U.S. backs some of the rebels fighting to overthrow him.

Kerry declined to go into the details of the agreement, saying it "is not yet done."

"The modalities for a cessation of hostilities are now being completed," Kerry said, adding that it was "possible over the course of these next hours."

Assad meanwhile said his government was ready to take part in a truce as long as it is not used by militants to reinforce their positions.

"We announced that we're ready," Assad told Spain's El Pais newspaper in remarks published Sunday.

"It's about preventing other countries, especially Turkey, from sending more recruits, more terrorists, more armaments, or any kind of logistical support to those terrorists," Assad said in English in the interview, which was also carried by state news agency SANA.

Assad's government refers to all the armed groups battling to overthrow him as terrorists. Turkey and Saudi Arabia are among the leading supporters of the insurgents.

Assad said the Aleppo operation is not about "recapturing the city," but "closing the roads between Turkey and between the terrorist groups."

The United States, Russia and other world powers agreed Feb. 12 on a deal calling for the ceasing of hostilities within a week, the delivery of urgently needed aid to besieged areas of Syria and a return to peace talks in Geneva. Aid shipments were allowed into several besieged areas last week.

German Foreign Minister Frank-Walter Steinmeier said he welcomed the latest provisional agreement and called on all regional powers to use the "window of opportunity" to exert their influence on the warring parties.

In northern Syria, meanwhile, the Syrian army captured 31 villages on Sunday that were controlled by IS, according to the pro-Syrian Lebanon-based Al-Mayadeen TV and Hezbollah's Al-Manar station. Both outlets often have reporters embedded with Syrian troops.

