Perhaps in response to the Western airstrikes, the Qaddafi forces are increasingly plunging into combat in equipment similar to what the rebels are using, mainly pickup trucks mounted with machine guns or rockets. The move makes it increasingly difficult for even the combatants to distinguish one group from the other at first sight.

“It’s a mistake,” said Abdul Hafidh Ghoga, the rebel’s main spokesman. “Nothing has changed.”

One rebel fighter who was wounded in the airstrike said a fellow rebel had fired into the air moments before the attack.

“I don’t know why,” the rebel, Ali Abdullah Abubaker, said later from a hospital in Benghazi. “Maybe he was scared.”

Seconds later, Mr. Abubaker heard the planes. “I saw something white,” he said. “There was no sound.”