(CNN) -- Two videos newly posted on YouTube show what Syrian opposition activists say is the gruesome slaughter of civilians in the besieged city of Daraa who had tried to feed people during a recent uprising.
One video shows what appears to be a group of Syrian security forces standing over dead bodies, making jokes and discussing planting weapons on them.
The gruesome images include the bloody, mangled bodies of five men in civilian clothes. They lie close together on a rooftop, in pools of blood. A group of men dressed in military uniforms walk around them, talking. "Show me those weapons," one says, "put them here."
Someone drops what seems to be weaponry onto the torso of one of the bodies.
"These are the weapons the committee will come film," a voice says.
Throughout the uprising in Syria, the Syrian government has described protesters as "armed criminals" and "terrorists," at times saying photos prove that the "criminals" were armed when security forces shot them.
In the video, the people speaking know they are are being taped, addressing the camera at times. Some of them are smiling or laughing. One jokes about "eyeliner" on one of the dead bodies.
Another video of what appears to be the same scene at a different point in time shows the dead bodies. A young man in military uniform then turns to the camera himself and says, "These are his criminals." It is not clear who he is referring to.
The gory videos -- in which the bodies are bleeding from different areas -- are labeled online as having been shot April 30.
CNN cannot independently confirm the authenticity of the videos.
Two activists with the Syrian opposition explained the incident. One is Abdullah Abazeed, an activist in Daraa, Syria, where the videos were apparently taken. The other activist, who spoke to CNN on condition of anonymity, is in the United States and helps Syrian activists post videos online.
Abazeed said members of his group, the Syrian Revolution Coordinators Union, negotiated the purchase of the two videos from a member of the security forces for 200 Syrian pounds ($40 U.S.) and put them on YouTube.
The incident took place in Daraa, which was under siege by Syrian security forces. Four of the men were working out of a mosque in Daraa, supplying food rations to people, the activists said. Two were the sons of Daraa-Abu Ibrahim, the man who calls for the prayers at the mosque; another two were his nephews, the activists said.
Syrian forces marched into the mosque and took the four men, along with a fifth unidentified man, to the roof of a neighboring building, the activists said. The mosque's minaret is visible in the background of the videos. The forces shot the men at point blank range, the activists said.
Members of the security forces took videos themselves, the activists said.
On April 30, Ibrahim -- whose sons and nephews were just killed -- was forced into making a statement on Syrian state television, the activists said.
Syrian state television aired video of Ibrahim making a statement at the time.
"The army came to me and asked me for help so I can move a group of people on the roof of the mosque," he said. He added that he was "surprised to find my son was inside. I told him, 'My son, surrender and leave.' I tried twice, and three times and then took myself and left."
He said he told the army lieutenant what had happened, who then told him to go back again.
"There was a gunfight between the army and the group inside which included my children and my nephews," Ibrahim said on state TV. "The thought that they could get martyrdom and their idea was to get freedom. Freedom is not gotten this way, not by means of killing, never ever by killing."
He added that he "saw them carrying weapons and killing and shooting at the army."
The opposition activists told CNN that Ibrahim's statement was coerced by Syrian security forces, who threatened the rest of his family.
Throughout the uprising, the Syrian government has generally ignored requests for comment from CNN, which has not been granted access into the country and is unable to independently verify the accounts.
A call to the Syrian embassy press office Sunday was not immediately returned.
CNN's Josh Levs and Yousuf Basil contributed to this report.