Russia’s Channel One television showed footage of four suspects and their damaged white Renault car.
It said they were captured by special forces in the village of Khatsun in the western Bryansk region, which is close to borders with Ukraine and Belarus.
In footage shot at night and in daylight, the detained men speak Russian with an accent.
The Islamic State (IS) group has claimed responsibility for Friday night’s attack, when a group of gunmen opened fire at Crocus City Hall concert venue near Moscow and set it ablaze.
They killed at least 133 people.
The interior ministry said Saturday that all four suspected gunmen were foreign nationals.
A Russian MP has said some of those detained are from Tajikistan, an impoverished post-Soviet state that borders Afghanistan and whose nationals have participated in previous IS attacks.
“What were you doing at Crocus?” a young bearded man seated on the ground is asked.
“I shot people.. for money,” he answers in broken Russian. He goes on to say he was offered “half a million rubles ($5,425)” and had received half of it on a bank card.
– Contacted on Telegram –
Those who had hired them had supplied them with the weapons, he added, corresponding with him on the Telegram secure messaging platform without giving their names.
The footage also shows one suspect being led along on a snowy track in a forest. The dark-haired man in a light brown T-shirt has blood pouring down his cheek from his ear.
He too is shown being questioned with a bandage wrapped around his head, his lips and nose bloodied and swollen.
Asked what the suspected attackers did with their weapons, he says they were left “somewhere on the road”.
Earlier, a graphic video was posted online, apparently showing the detention of the same suspect.
It showed a man in camouflage cutting off part of the ear of a dark-haired man, trying to make him eat it and then hitting him on the face.
Russian television showed other suspects with cuts to their faces.
Chechen leader Ramzan Kadyrov said that Chechen soldiers had helped the FSB security service capture the suspects.
Belarus said that it had assisted Russia in detaining the men “to prevent them from leaving through our common border”.
None of those questioned mentioned either Islamic State or Ukraine in the footage broadcast.
Russian officials have not mentioned the Islamic State group in their public statements, but President Vladimir Putin said Saturday the suspects had been planning to cross the border into Ukraine.
Kyiv firmly denies any involvement and has dismissed any suggestion the gunmen could have been heading into Ukraine.
Russia has said it has detained 11 people including four suspected gunmen.
AFP