Gunfire struck a helicopter carrying election material in eastern Libya on Friday, killing one man, security sources told Al Jazeera.
The deadly attack near the city of Benghazi was the latest in a string of violence and protests to hit the east in the runup to Saturday's vote for a constituent assembly - the first election since rebels overthrew longtime ruler Muammar Gaddafi last year.
The helicopter was forced to land at nearby Benina International Airport after the incident, the military said.
"A helicopter carrying ballots and flying over the region of Hawari was struck by small arms fire," army spokesman Colonel Ali al-Sheikhi told the AFP news agency.
An official of Libya's electoral commission said a colleague was killed in the incident.
"We were preparing to receive the voting material as it arrived on a helicopter from Tripoli but it was hit and one man died," Ahmed Abdelmalik, an employee at the local branch of the election commission, told the Reuters news agency.
Hamed Al-Hassi, head of the military council for the Cyrenaica region, told Reuters that the identity of the attackers was not immediately known.
Two rockets hit Benghazi Medical Centre earlier on Friday without causing casualties or damage, according to Ala Ben al-Kazza, an official at the hospital.
The east of the country, known was Cyrenaica, has witnessed ongoing protests and unrest by local groups who are seeking greater autonomy under a federal system and are upset with what they see as an unequal distribution of seats in the new assembly.
Protests had earlier forced the closure of three ports, shutting down roughly half of Libya's oil exporting capacity, and on Thursday, the main storage centre for election materials in the eastern town of Ajdabiya was badly damaged in a suspected arson attack.
"We expected this issue," Emad El-Sayih, deputy head of Libya's High National Election Commission, told Reuters. "There is no security in this country - the interior ministry and the army are incapable of protecting the elections. The (election) commission is in a state of depression."
Source: Al Jazeera and agencies