Libya's rebel capital of Benghazi was tense Friday, as gunfire reportedly erupted in the streets of Benghazi amid preparations for the funeral of the opposition's slain military chief.

The rebel leadership council says its top military commander, Abdel Fattah Younes, and two of his aides were shot dead by unknown assailants on Thursday.

Transitional National Council head Mustafa Abdel Jalil said that Younes and his aides – both colonels – were killed before arriving for questioning at an opposition judicial committee hearing regarding a “military matter.” He said the head of the armed cell that killed the men had been arrested.

Jalil never clearly indicated who he thought was behind the attack. He says the rebels will observe three days of mourning.

The rebels said they had detained Younes on suspicion his family may still have ties to Mr. Gadhafi's inner circle.

Younes had been the Libyan leader's interior minister and one of his closest confidants before unexpectedly defecting to the opposition early in the uprising, which began in February.