Tripoli, Libya (CNN) -- An amateur league of ill-trained rebel fighters appears to be on the brink of toppling Moammar Gadhafi's 42-year rule after reportedly capturing two of the leader's sons and infiltrating the Libyan capital. But in a possible indication that the fight is not over, celebrations in Tripoli's Green Square -- renamed Martyrs' Square by the rebels -- gave way to tension Monday morning after rebels told CNN that they'd heard Gadhafi army forces were heading their way. CNN could not confirm any movement of Gadhafi forces. The uncertainty came hours after a rebel official said two of Moammar Gadhafi's sons -- Saif al-Islam and Saadi -- had been arrested by opposition forces. Jumma Ibrahim, a rebel spokesman based in Libya's western mountain region, said both were captured in Tripoli.
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Rebels in the capital include the "Tripoli Brigade," consisting of ex-Tripoli residents
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Rebel fighters scatter from Green Square amid fears Gadhafi forces are nearing
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Two of Gadhafi's sons -- Saadi and Saif al-Islam -- are arrested, a rebel official says
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Their father earlier urged Libyans to fight to "lead the people to paradise"
To prevent such bloodshed, he said, @placeholder, including women, should go out and fight.