A vacationing President Barack Obama is being kept up to date by aides as reports come in of rebel troops advancing on Libya's capital, Tripoli.
A senior administration official reports the president was briefed during the day Saturday on Martha's Vineyard, and is continuing to get regular updates. The official spoke on condition of anonymity because of the sensitivity of the situation.
Reporters in Tripoli heard gunfire and explosions after rebel troops seized control of Brega, a major coastal city not far from the capital. Rebel leaders called it the start of an attack on Moammar Gadhafi's main stronghold.