Ambulances, sirens blaring, could be heard racing through the Libyan capital after the rattling blasts. A NATO statement said the attacks hit military vehicle and ammunition depots, a surface-to-air missile launcher and a fire-control radar system.
Libyan government officials refused repeated requests for information.
The airstrikes rained down just hours after NATO and its partners said they would extend the Libyan mission for 90 days in support of the rebel insurgency. The opposition is trying to oust Moammar Gadhafi, who has ruled Libya for more than 40 years. The rebels have taken control of much of eastern Libya.
Extending the mission also reflects the Gadhafi regime's resilience. The government is hanging on to power despite NATO strikes that have targeted military sites and the ruling family since mid-March, as well as a naval blockade and top defections from the government and military.
Some Republicans and Democrats say they are frustrated with the inability of President Barack Obama's administration to explain the U.S. mission. They argue that Obama violated the law by failing to seek congressional authorization 60 days after military operations began.