BEIRUT, Lebanon — When the predawn blasts rattled their windows and jolted them from sleep, residents of Raqqa, the Syrian city that is the de facto capital of the Islamic State, thought they were in for a new round of airstrikes from the Syrian government.

But as the sun rose, it was quickly clear that something altogether different had taken place. A drone had collided with a satellite tower and crashed to the ground. The former governor’s office used as a headquarters had been reduced to rubble. An equestrian club where fighters had lodged their families and a training camp near town had also been bombed.

Even after a year living under the fist of the so-called Islamic State, where men with guns and a messianic vision controlled nearly every aspect of their lives, the people of Raqqa were surprised by what they found.

“I opened my shop at 8 a.m., and everything was ordinary,” said a shopkeeper who gave his name as Abu Khalil. “Then I heard from my neighbor that today’s attacks were by the Americans, and not the regime.”