A boy stands in front of a shop destroyed by Syrian army shelling in the center of Idlib on Monday. (Rodrigo Abd/AP)

The bodies of dozens of men were found dumped on wasteland on the outskirts of the stricken city of Homs on Monday in what appeared to be one of the worst instances of mass killing since the uprising against President Bashar al-Assad began last March.

The Local Coordination Committees, an opposition group, said that the bodies of 64 men were taken to the National Hospital in Homs and that an unknown number of women and children who had been with them are missing. Activists said they thought that the men had been trying to flee the violence with their families when they were stopped and gunned down by security forces.

The details available were murky, however, and the bodies had not been identified, making it difficult to establish exactly how or why the men died.

The discovery came as Syria’s state media announced that a big majority of Syrians had voted to approve a new constitution that would allow Assad to remain in power until 2028. U.S. and European leaders have condemned the exercise as meaningless, since it seemed designed primarily to ensure Assad’s survival rather than to implement genuine reforms.

The apparent mass killing in Homs spoke to the rising ferocity of the violence engulfing many parts of Syria as the government seeks to quell the revolt and the once-peaceful protest movement increasingly resorts to arms to resist the onslaught, stirring fears of a civil war that could ignite a wider regional conflict.

The deaths were among 124 reported across Syria on Monday as the government’s efforts to crush the nearly year-long uprising showed no sign of letting up.

They included an additional 25 victims of continued shelling of the Bab Amr neighborhood in Homs, which has been subjected to daily bombardments by tank and artillery fire in a massive offensive that began Feb. 3.

The assault is aimed at crushing anti-government resistance in what had emerged as one of the biggest strongholds of the loosely organized Free Syrian Army rebel movement.

The official news agency SANA reported the funerals on Monday of 16 soldiers and policemen killed in the violence nationwide.

Homs has also become a flash point for sectarian tensions, which have escalated as the regime, dominated by members of Assad’s minority Alawite sect, has sustained its efforts to quell a revolt embraced by the country’s mostly Sunni majority. There have been recent instances of sectarian killings in the city, and some activists said they could not rule out a sectarian dimension to this apparent massacre.

Trying to flee

Activists contacted in Homs said they thought the men were killed mainly because they were originally from Bab Amr. Fighting had displaced them weeks ago to outlying areas of the city, which they sought to flee overnight Sunday when those areas came under heavy attack.

Abu Emad, who spoke from Homs via Skype, said the men were among a large group of families that were leaving those areas when their vehicles were stopped at a checkpoint close to the main highway leading to Damascus.

The families were herded onto four buses, he said, citing the accounts of survivors, and were told they were being taken to a safe place. After a short distance, the elderly passengers were ordered off the buses, and the rest were driven away. On Monday morning, local residents discovered the bodies of the men; the whereabouts of the women and children who were with them are unknown, Emad said.

“They killed all the young men,” he said. “Maybe there are more — we still don’t know.”

The human rights group Avaaz gave a similar account of the incident but put the number of bodies found at 62. The Britain-based Syrian Observatory for Human Rights said 68 bodies had been taken to the National Hospital. Some of the victims had been shot, and others were bayonetted to death, said the Observatory’s spokesman, Rami Abdulrahman. He said it was not clear who the men were or why they were killed.

The accounts could not be independently confirmed; nor could the reports of killings elsewhere in the country, because journalists are not being granted visas to work in Syria.

Among those trapped in besieged Bab Amr are two foreign journalists who had entered the country illegally and were injured last week in a rocket attack that killed American journalist Marie Colvin, who was working for the British Sunday Times, and French photographer Remi Ochlik.

According to the Associated Press, Poland’s foreign ministry has started an effort to negotiate safe passage out of the area for the two injured journalists, Edith Bouvier of the French newspaper Le Figaro and British photographer Paul Conroy of the Sunday Times, as well as the bodies of the two who were killed. Poland undertook to represent U.S. interests in Syria after the closure of the U.S. Embassy in Damascus this month.

A new constitution

SANA reported that 89.4 percent of voters in Sunday’s referendum endorsed the constitution, which was unveiled less than two weeks before the balloting amid Russian pressure on Assad to head off escalating Western efforts to force his departure.

The interior minister, Mohammad Ibrahim al-Shaar, was quoted as saying that 8,376,447 citizens, or 57.4 percent of eligible voters, voted in the referendum.The turnout was “good,” Shaar said, “despite the threats and intimidation by armed terrorist groups in some areas and the accompanying distortion and instigation campaigns by media.”

But with foreign journalists and outside observers barred from witnessing the polling, the opposition boycotting and violence raging across many parts of the country, the validity of the vote or the result was impossible to verify.

Though the new constitution introduces term limits and allows multiple political parties to compete in elections, it concentrates so much power in the presidency that Assad would effectively be able to remain in office 16 more years.

Russian Foreign Minister Sergei Lavrov nonetheless hailed the outcome as a “movement toward democracy,” and Russian Prime Minister Vladimir Putin reiterated his opposition to any military intervention in Syria.

“I strongly hope that the United States and other nations will learn from the sad experience and won’t try to resort to a forceful scenario in Syria,” Putin wrote in a foreign policy manifesto published in Russian newspapers.

The comments followed an effort on Friday to rally support for Assad’s ouster by a new, U.S.-backed Friends of Syria group, which was set up as a forum to support the Syrian opposition after Russia and China closed the door on U.N. action by vetoing a Security Council resolution.

Although the group, including European and Arab nations and the United States, affirmed its support for Assad’s ouster, it stopped short of offering aid to the divided and ill-defined Syrian opposition.

Also Monday, a new group called the Al-Nusra Front to Protect the Levant said it was behind a double suicide bombing in Aleppo this month and a Jan. 6 bombing in Damascus that killed dozens.

In a videotaped message posted on a jihadi Web site that recounted details of the attacks, the group vowed to avenge the killings of Syrians by government forces wherever they occur and said that only armed revolt would bring down the Assad regime. It was the first claim of responsibility for the bombings, and though it could not be verified, the group’s video comes amid growing concerns that al-Qaeda-linked groups are attempting to infiltrate the Syrian uprising.