Rebels ransacked Gadhafi's compound Tuesday, but found no sign of the longtime leader.
For the first time in days, the 69-year-old Gadhafi addressed the country from a hidden location, urging supporters to continue to fight and free Tripoli of the "devils and traitors" who have overrun it.
The rebels claim they control 80 percent of the capital. Members of Libya's National Transitional Council began moving from Benghazi to Tripoli where they intend to set up a new government.
The National Transitional Council announced a $2 million bounty for Gadhafi.
During Libya's six-month civil war, opposition leaders had established their interim administration, the National Transitional Council, in the eastern city of Benghazi, which fell under rebel control shortly after the outbreak of widespread anti-regime protests in February.
Meanwhile, dozens of foreign journalists were released Wednesday after being held captive for days by pro-government gunmen at Tripoli's once-luxurious Rixos Hotel.
A steady barrage of machine gunfire and heavy weapons could be heard in the surrounding area, including in a large wooded park behind the hotel.
In Brussells, a NATO official said warplanes continued to strike overnight at pro-Gadhafi forces.
Experts said foreign support for the rebellion will be critical in the future to keep the loose tribal alliance from falling apart.
The Associated Press contributed to this report.