Syrian government forces overran an opposition stronghold in the central city of Homs on Thursday, raising concerns about the safety of the civilians still trapped there and exposing the limitations of the fledgling armed resistance movement that has sprung up to confront the Syrian regime in recent months.

Opposition activists in Homs said troops were moving through the Bab Amr neighborhood detaining all males older than 15 , even as world powers at the United Nations issued a nonbinding Security Council resolution calling for immediate humanitarian access to the stricken area.

With all communications to Bab Amr severed, including satellite connections, it was difficult to ascertain exactly what was happening. But though the rebel Free Syrian Army cast the pullout as a tactical withdrawal, all the available evidence pointed to a rout of the fighters, who had seized control of the neighborhood months ago and turned it into a nationwide symbol of the burgeoning armed rebellion against the regime led by President Bashar al-Assad.

The speed with which Syrian forces seized control of the neighborhood — less than 36 hours — after a 27-day siege during which the area was subjected to almost-uninterrupted artillery bombardment, focused attention on the increasingly controversial question of whether outside powers should arm the Syrian opposition.

Col. Malik al-Kurdi, a Free Syrian Army spokesman reached by telephone in Turkey, appealed for weapons, saying that only the force of arms could bring down the Assad regime and protect the civilians who have been demonstrating for nearly a year to end four decades of Assad family rule. “Our light and limited weapons cannot confront the tanks and rockets of the regime,” Kurdi said.

Saudi Arabia and Qatar have in recent days declared support for arming the Free Syrian Army. But the United States remains opposed, amid concerns about the nature of the deeply divided Syrian opposition and the risk of a regionwide conflagration should a full-scale civil war erupt.

The retreat from Bab Amr also called into question the capacity of the disorganized rebel movement to confront one of the region’s most powerful armies, even if weapons do begin to flow. The fighters are equipped only with Kalashnikovs and rocket-propelled grenades seized from the regular army or smuggled across Syria’s borders.

“The Free Syrian Army don’t have heavy weapons, and without them I’m not sure they can survive,” said Mulham Jundi, a member of the opposition Syrian National Council who is in hiding in Homs.

A statement issued by the Free Syrian Army said its fighters had withdrawn out of consideration for the welfare of the 4,000 civilians trapped in the neighborhood, and because they lacked sufficient weaponry to withstand a stepped-up ground offensive by the better-armed government troops.

In a statement posted on a Facebook page run by Bab Amr activists, the rebels cited dire conditions in the area and called on the Red Cross to be allowed to deliver humanitarian aid.

“We, the Bab Amr brigade, have decided to strategically withdraw for the sake of the civilians remaining inside the neighborhood,” the statement said. “The humanitarian situation is at its worst, as there is no food whatsoever, no medicines, no water and no electricity.”

Activists in Homs said, however, that the rebels began fleeing overnight Wednesday when they ran out of ammunition as government ground forces closed in on the neighborhood. Food ran out days ago, the water supply is cut off and fuel has dried up, leaving residents freezing as snow falls and activists are unable to power the laptops and satellite phones they had used to stay in touch with the outside world.

“Following a month of heavy bombardment and shelling from tanks, rockets, mortars and all kinds of heavy weapons, the Free Syrian Army could not hold on longer,” Kurdi, the spokesman, said.

Government tanks and artillery pounded areas through which the rebels fled, and many are feared to have died in the bombardments. A group of 17 men was intercepted as they sought to escape through an area of farmland adjoining Bab Amr; they were reportedly beheaded.

The Local Coordination Committees, an opposition group, said it had confirmed the deaths of 26 people in Homs on Thursday, but the count did not include those who may have been killed in Bab Amr and its immediate surroundings.

Jundi, the activist contacted in Homs, said fleeing residents had told him that all males in the neighborhood were being detained in a mass arrest campaign. Activists said they feared for the safety of everyone left behind.

“We are very concerned about the civilians because the history of this regime means they are likely to kill everyone who is there,” said Wissam Tarif, a Beirut-based activist with the advocacy group Avaaz.

The International Committee of the Red Cross said it had been granted permission by the Syrian government to deliver humanitarian aid on Friday. But a spokesman in the United States, Simon Schorno, cautioned that the organization would have to assess the security situation before deciding whether it was safe to send in a team.

The U.N. Security Council’s call for “immediate, full and unimpeded access” to Bab Amr and other areas subjected to the government crackdown did not carry the full force of a resolution, but it was nonetheless significant because Russia and China, which have blocked past efforts to sanction Syria at the United Nations, signed onto it.

Activists vowed that the fall of Bab Amr would not spell an end to the uprising, which erupted in mid-March as a spontaneous outpouring of resentment against decades of dictatorial rule only to be confronted by a massive crackdown.

The focus on Bab Amr has detracted attention from many other areas of the country that are also in open revolt and are enduring government attacks, said Rami Jarrah, a Syrian who fled the crackdown in Damascus last fall and helps run the Activist News Association in Cairo.

“The Syrian government, due to its brutality, has the upper hand,” he said. “This is a setback, but it does not at all mean the downfall of the revolution. That, I am sure, is mission impossible.”

Syrian state television trumpeted the seizure of Bab Amr, which the government said had been taken over by “terrorists,” by broadcasting footage of Assad supporters streaming through the battered streets in convoys of vehicles. The official Syrian Arab News Agency also said that the authorities had recovered the corpses of two journalists killed in the neighborhood during a rocket bombardment last week.

The bodies of American journalist Marie Colvin, who worked for Britain’s Sunday Times, and Remi Ochlik, a French photographer, were found and will be transferred to a Damascus hospital, the agency said. However, SANA said the body of a third journalist, Javier Espinosa, who is alive and has left Syria, was also found, calling into question the reliability of the report.

A videotape released earlier by activists had shown the bodies of Colvin and Ochlik being buried in an undisclosed location in Homs.

French officials said Thursday that two French journalists, Edith Bouvier and William Daniels, who had been trapped in Homs for several days, had made their way out of the country and were in Beirut.

Staff writers Karen DeYoung and Carol Morello in Washington and Colum Lynch in New York contributed to this report.