Thousands of Libyan protesters rallying in the eastern city of Benghazi to press for an autonomous region came under attack by armed men wielding rifles and knifes, witnesses said.
"One person was killed and at least five others were wounded," Basma Mohammed, a local medical official, told the AFP news agency.
One of the protesters, Bashar al-Denali, said armed assailants charged into the crowd and opened fire. Protesters panicked and fled the square was then occupied by the armed men, he said.
Another protester Omar al-Mesmari said assailants attacked an office of a local Libyan television station, Libya Al-Ahrar, to prevent it from covering and broadcasting the demonstration.
Benghazi militia fighters, who are responsible for security in the city, deployed forces and chased the attackers, witnesses said.
The marchers gathered after Friday prayers and went to Freedom Square, where Ahmed Zubeir Senussi, who is calling for autonomy in the oil-rich east of the country, delivered a speech.
Senussi and the demonstrators were showing their support for a declaration by tribal leaders and militia commanders in the eastern Barqa state to create an autonomous region. Barqa makes up almost half of Libya.
Supporters say the step is necessary to end the marginalization their region suffered for decades under Muammar Gaddafi's rule, toppled in October at the hands of citizens-turned-fighters after an eight-month uprising.
The former dictator focused development and largesse on the western part of the country, allowing infrastructure to decline in the east, an area that was a constant source of opposition to his regime.
But the move to create an autonomous region has created a strong backlash among opponents who fear it will eventually lead to the disintegration of the country.
Protesters in the rally denounced what they called attempts by those in western Libya to control the eastern part of the country.