OUAGADOUGOU, Burkina Faso — Terror came to this sleepy city this weekend, as armed fighters descended on a road nicknamed the Champs-Élysées, where friends meet for coffee and foreigners relax in a familiar hotel. After a 15-hour siege, the assailants left behind more than the dead and wounded scattered across the charred road amid shell casings.

The rampage at the Splendid Hotel and Cappuccino Cafe here in the capital forced this nation to face the awful realization that the violent Islamic extremism that it for years avoided finally had crept across its borders.

Twenty-eight people were killed and 56 were wounded in the attack that loudly announced the end to a long, mostly peaceful stretch in Burkina Faso. A State Department statement on Saturday identified an American, Michael James Riddering, as one of the casualties.