Mourners turned out in Libya's rebel capital of Benghazi on Friday for the funeral of the opposition's slain military chief, gunned down Thursday along with two of his aides.

The Associated Press says thousands of people turned out for the funeral procession for Abdel Fattah Younes.

The head of the opposition Transitional National Council said that Younes and his aides – both colonels – were killed before arriving for questioning at an opposition judicial committee hearing regarding a “military matter.”

Mustafa Abdel Jalil also said Thursday that the head of an armed cell that killed the men had been arrested.

However, Jalil never clearly indicated who he thought was behind the attack.

Earlier, rebels said they had detained Younes on suspicion his family may still have ties to leader Moammar 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.