Libya's Interior Ministry said four policemen were killed in a rocket-propelled grenade attack on a security unit in Benghazi today, reported the Associated Press.
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Police spokesman Khaled Hidar told Reuters the attack sparked an exchange of fire.
"It was a long battle," Hidar said. "Three other policemen were severely injured."
Another police spokesman, Ezzedine al-Fazani, told AP the violence was believed tied to the arrest of a man accused of being involved with an assassination attempt of a security chief last month.
The police chief in question was killed last month, according to Reuters.
Fazani told AP the attackers seemed to aiming for a nearby detention center in which the man is being held.