Serbian police have arrested at least eight men they say are shown in a video killing a group of Bosnian Muslim prisoners from Srebrenica, a top Belgrade (search) official said Thursday.

Up to 8,000 Bosnian Muslim men and boys were killed in Srebrenica in 1995 — Europe's worst mass killing since World War II.

The arrests came after the footage was shown Wednesday at the U.N. court in The Hague (search), Netherlands, said Rasim Ljajic, head of the Serbia-Montenegro government body in charge of cooperation with the U.N. war crimes tribunal.

The footage was also broadcast late Wednesday by several television channels in Serbia and stunned the Balkan republic.

"Serbia is deeply shocked," President Boris Tadic (search) said. "Those images are proof of a monstrous crime committed against persons of a different religion. And the guilty had walked as free men until now."

The amateur footage, apparently made by Serb troops, showed six civilians taken from a truck, hands tied behind their backs and lined up on a hillside. Four were shot one by one in their backs. Two other prisoners were ordered to carry the bodies into a nearby barn where they too were killed.

The prosecution introduced the film during the hearings in the trial of former President Slobodan Milosevic (search), indicted for his alleged role in atrocities during the Balkan wars, including the Srebrenica massacre.

U.N. prosecutors contend the killings were carried out by the Serb paramilitary unit known as the Scorpions somewhere on Mount Treskavica near the wartime Bosnian Serb capital Pale. The Scorpions were allegedly under orders from Serbian police in Belgrade and the link could directly tie Milosevic with the crimes committed in Bosnia.

Tadic, Serbia's president, said the crimes at Srebrenica "were carried out in the name of our nation."

"But crimes are always individual and the perpetrators of these monstrous crimes must be caught and punished," he said.

Ljajic said those arrested in the police sweep were identified as the executioners shown in the footage. He said the police would "continue the sweep until all suspects are in custody."

Earlier Thursday during a visit to Belgrade by U.N. Chief Prosecutor Carla Del Ponte, Serbia's Prime Minister Vojislav Kostunica announced that "several suspects" from the footage shown at The Hague court were detained. Del Ponte praised the arrests as a "brilliant operation."