Libyan rebels say NATO planes mistakenly fired on them, killing at least 13 people and destroying five vehicles on the road between Brega and Ajdabiya late Friday night. Details of the incident are unclear, and NATO says it's investigating. A BBC correspondent says the rebels may have fired an antiaircraft gun in the air in celebration, causing a coalition plane to fire on the convoy. But a rebel fighter says some of “Gaddafi's forces sneaked in among the rebels and fired antiaircraft guns in the air," prompting the airstrike. A doctor in Ajdabiya says a coalition strike against a convoy of government tanks sent shrapnel into nearby houses, killing seven civilians. But the doctor said “there was no anger” at the coalition forces, because the opposition still relies on the protection the strikes afford them. "The exact details are hard to verify because we have no reliable source on the ground," said a NATO spokeswoman of the incident. "Clearly, if someone fires at one of our aircraft they have the right to defend themselves."