Russia has arrested 11 people including four suspected gunmen in connection with a shooting rampage that killed at least 143 people in a concert hall near Moscow, the Kremlin said Saturday.

Militant Islamist group Islamic State claimed responsibility for Friday¡¯s attack, the deadliest in Russia for 20 years. But there were indications that Russia was pursuing a Ukrainian link, despite a statement from Ukrainian presidential adviser Mykhailo Podolyak that Kyiv had nothing to do with it.

The FSB security service said ¡°all four terrorists¡± had been arrested while heading to the Ukrainian border, and that they had contacts in Ukraine. It said they were being transferred to Moscow.