Videos posted online showed what appeared to be the aftermath of the explosions.
In one video that the caption said was from Ard al-Hamra, dozens of people, many of them with flashlights, scour the rubble in the dark in search of survivors. In another clip, at least nine bodies are laid out on a floor, some of them wrapped in blankets.
The videos appeared authentic and corresponded to other AP reporting.
In Cairo, the Syrian National Coalition, an opposition umbrella group, said it would welcome U.S. and Russian mediation to negotiate a peace deal to end the country's civil wall but insisted it would not allow Assad or members of his security services to participate in the talks. The announcement came in a statement posted on the coalition's Facebook page following two days of meetings in Cairo meant to firm up the group's position on whether to engage in talks.
"Bashar Assad and the security and military leadership responsible for the state of Syria today must step down and be considered outside this political process," the statement said. "They cannot be part of any political solution for Syria and must be held accountable for their crimes."
Coalition chief Mouaz al-Khatib has angered some in the opposition by offering to sit down with regime figures to help end the civil war. Friday's announcement appeared aimed at setting the boundaries for any future talks by stressing that Assad and his aides cannot be part of any negotiations.
The Coalition also agreed to form a transitional government in rebel-held areas and said it will meet on March 2 in Turkey to choose a leader for the administration, spokesman Walid al-Bunni told reporters in Cairo.
The opposition umbrella group has been struggling to agree on the leadership of a provisional administration since the Coalition was formed late last year. The group has met on previous occasions to agree on an interim prime minister, but failed to reach a compromise.
Also Friday, Reporters Without Borders said French freelance photographer Olivier Voisin was seriously wounded a day earlier in Idlib province.
The media watchdog said Voisin sustained shrapnel wounds to his head and arm, and underwent surgery at a hospital in Antakya, Turkey.
Hospital officials in Turkey confirmed that Voisin was in the country for treatment. The officials spoke on condition of anonymity because they were not authorized to brief the media.
The New York-based Human Rights Watch urged the U.N. on Friday to require Syrian authorities to grant international monitors access to its detention facilities, following the death of a peace activist in custody.
Omar Aziz, 64, died on Feb. 16 of health complications at a military hospital, the group said in a statement. It also described how a newly released detainee also reported witnessing the death of Ayham Ghazzoul, an imprisoned 26-year-old rights activist. Both had been detained by security forces in November.
Human rights groups and the opposition accuse Syrian authorities of holding tens of thousands of prisoners, many of whom it is feared have been tortured.
Associated Press writers Zeina Karam and Ryan Lucas in Beirut, and Aya Batrawy in Cairo contributed to this report.
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