Evening vigils have been called across Libya to commemorate the life of one of the country's leading human-rights figures, Salwa Bugaighis, killed by armed men in the eastern city of Benghazi on Wednesday.
Attackers burst into Bugaighis' home, shooting and stabbing her, wounding a security guard and abducting her husband Issam al-Ghariani, a member of Benghazi council, who remained missing as of Thursday night.
The attack came as voting ended in Libya's general election, with election organisers reporting 630,000 people, or 18 percent of the potential electorate, casting a ballot.
Bugaighis had returned to Libya with her husband shortly before the election, insisting that despite death threats she would continue campaigning for women's rights.
The UN led condemnation of the killing, calling for the killers to be brought to justice, while Deborah Jones, US ambassador to Libya, said on Twitter: "I awoke this morning praying this was a horrible nightmare. Now we must all work to make real Salwa Bugaighis' dream of a free Libya."
Hanan Salah of Human Rights Watch said on Twitter: "Shocked and dismayed about murder of Salwa Bugaighis today. Her voice was vital for Libya."
UN women executive director Phumzile Mlambo condemned the assassination, saying on her Twitter account that it is "blow and Tragedy".
British ambassador Michael Aron tweeted that he was "Devastated" about horrific murder of Salwa Bugaighis.
Amnesty International called for a proper investigation on the killing.
"The shocking, ruthless killing of Salwa Bugaighis robs Libyan civil society of one its most courageous and esteemed figures. But sadly she is by no means the first activist struck down during the political violence that has plagued the country since the uprising and in its aftermath," said Hassiba Hadj Sahraoui, Amnesty International’s Middle East and North Africa Deputy Director.
Bugaighis, a lawyer, played a prominent part in Libya's 2011 revolution that overthrew Muammar Gaddafi, becoming a member of the first rebel government, the National Transitional Council.
Bugaighis became known as a leading activist, campaigning in favour of a quota for women in parliament, and for the right of women to choose whether to wear the hijab.
Her campaigning had brought her into conflict with the Muslim Brotherhood over her call for Islamic sharia to be only one source of law for Libya's constitution.
Shortly before her death she posted photographs showing her voting in Wednesday's election, the second held by Libya since the end of the revolution.
Mohamed, a Tripoli student, told Al Jazeera: "So many people respected her for what she said, she was always calling for civil dialogue."
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Her killing came as violence flared in Benghazi in battles between troops and armed groups that left three soldiers dead.
On Thursday, a car bomb detonated outside the offices of Libya's constitutional assembly, wounding two, in the eastern city of al-Bayda.
The assembly, elected in February to design Libya's constitution, labelled the bombing a "terrorist criminal act aimed to obstruct the work of the assembly, and distract it from the peaceful path of democracy."
In Tripoli, rival militias took to the streets, and amid fears of violence the country's supreme court postponed its scheduled session and the Foreign Ministry was evacuated.
The election organiser, the High National Elections Commission, has given no date for final results for Wednesday's ballot, which will see a 200-seat House of Representatives replace the former General National Congress.
Fears of widespread and violence on election day appeared be unfounded. Several dozen polling stations disrupted by attacks and the burning of ballot boxes, but organisers said most of the country's 1,300 polling stations operated normally.