Muammar Gaddafi, the toppled Libyan leader, has been killed near his hometown, Sirte.
"We have been waiting for this moment for a long time. Muammar Gaddafi has been killed," the de facto Libyan Prime Minister Mahmoud Jibril told reporters in Tripoli.
Abdul Hakim Belhaj, an NTC military chief, said Gaddafi had died of his wounds after being captured on Thursday.
The body of the former Libyan leader was taken to a location which is being kept secret for security reasons, an NTC official said.
"Gaddafi's body is with our unit in a car and we are taking the body to a secret place for security reasons," Mohamed Abdel Kafi, an NTC official in the city of Misrata, told Reuters news agency.
Earlier, Abdel Majid, another NTC official, said the toppled leader had been wounded in both legs.
The news came shortly after the NTC captured Sirte, Gaddafi's hometown, after weeks of fighting.
"Thank God they have caught this person. In one hour, Sirte was liberated," a fighter in the town said.
In Tripoli, Jibril said he had received unconfirmed reports that Gaddafi's most prominent son, Saif al-Islam, was in convoy fleeing Sirte.
Meanwhile, there were conflicting reports about the fate of one of his sons, Mutassim Gaddafi.
Reuters reported that one of the news agency's sources had seen video of Mutassim lying on a bed and covered in blood, but alive.
Mahmoud Shammam, the NTC's information minister, said he had received reports that Mutassim had been captured alive in Sirte, but could not confirm the news.
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However, Mohamed Leith, an NTC commander, told the AFP news agency that Mutassim had been killed.
"We found him dead. We put his body and that of [former defence minister] Abu Bakr Younus in an ambulance to take them to Misrata".
Footage had emerged earlier in the day of the body of Younus.
Abdul Hakim Al Jalil, commander of the NTC's 11th brigade, said that Moussa Ibrahim, former spokesman for Gaddafi's fallen government, had been captured near Sirte.
NATO and the US state department said they could not confirm any reports.
Meanwhile in Benghazi and Tripoli, crowds gathered in the streets to start celebrating the death of Gaddafi.
Al Jazeera has acquired exclusive footage of the body of Muammar Gaddafi after he was killed in his hometown, Sirte.
Abdul Hafiz Ghoga, vice chairman of Libya's National Transitional Council, confirmed that the ousted leader had been killed on October 20, 2011 near Sirte.
"We announce to the world that Muammar Gaddafi has been killed at the hands of the revolutionaries," Ghoga told a news conference in Benghazi - Al Jazeera
The news came shortly after the NTC captured Sirte after weeks of fighting.