BEIRUT — Lebanese protesters erected flaming roadblocks and gunmen roamed the streets Saturday in a city on edge after the assassination of a top security official in a powerful car bomb the prime minister linked to the civil war in neighboring Syria.

The crisis raised a terrifying specter for Lebanese who fear their country could easily plunge back into cycles of violence and reprisal that have haunted it for decades.

Friday’s blast in the heart of Beirut’s Christian area killed eight people, including the country’s intelligence chief, Brig. Gen. Wissam al-Hassan. It was the deadliest bombing in Beirut in four years, shattering the country’s uneasy calm.

The government declared a national day of mourning for the victims Saturday, but protesters burned tires and set up roadblocks in anger.

Sharbal Abdo, who lives in the neighborhood where the bomb went off, brought his 6-year-old son, Chris, and 12-year-old daughter, Jane, to see the destruction Saturday.

“They were very afraid yesterday,” he said. “They need to face this situation. It may be their future.”

Lebanese Prime Minister Najib Mikati on Saturday linked the bombing to al-Hassan’s high-profile investigation this summer that uncovered what authorities called a plot by Syria to provoke chaos in Lebanon with bombings and assassinations.

“I don’t want to prejudge the investigation, but in fact we cannot separate yesterday’s crime from the revelation of the explosions that could have happened,” Mikati said at a news conference following an emergency Cabinet meeting.