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.

Mikati, who opponents believe is too close to Syria and the Shiite militant group Hezbollah, offered to resign after the bombing, but was asked by President Michel Suleiman to stay.

Al-Hassan’s probe led to the arrest of former Information Minister Michel Samaha, one of Assad’s most loyal allies in Lebanon. Samaha, who

is in custody, is accused of plotting a wave of attacks in Lebanon at Syria’s behest. Indicted in absentia in the August sweep was Syrian Brig. Gen. Ali Mamlouk, one of Assad’s highest aides.

Samaha’s arrest was an embarrassing blow to Syria, which has long acted with impunity in Lebanon. Syria has powerful allies here, including the Shiite militant group Hezbollah, which now dominates the government.

For much of the past 30 years, Lebanese have lived under Syrian military and political domination.

Damascus’ hold on Lebanon began to slip in 2005, when former Prime Minister Rafik Hariri was assassinated in truck bomb along Beirut’s Mediterranean waterfront. Syria denied having any role. But broad public outrage in Lebanon forced Syria to withdraw its troops from the country.

The killings of anti-Syrian figures continued for years, however, and Assad has managed to maintain his influence in Lebanon through Hezbollah and other allies.

Now, as the Syrian civil war rages just across the border, Lebanon increasingly is getting sucked in.

Mikati said Saturday he had offered to resign after Friday’s car bomb, but said Suleiman asked him not to plunge the country into more uncertainty.

The bombing raised fears that the crisis could unleash Lebanon’s sectarian tensions, a dire scenario for a country that endured a devastating civil war of its own from 1975-1990.

The Syrian unrest has already enflamed tensions here. Many of Lebanon’s Sunni Muslims have backed Syria’s mainly Sunni rebels, while Shiite Muslims have tended to back Assad.

Al-Hassan was a Sunni whose stances were widely seen to oppose Syria and Hezbollah.

Hundreds of Sunni protesters marched in force through downtown Beirut Saturday, placing the blame squarely on Syria and Hezbollah for al-Hassan’s killing.

“Hezbollah is a terrorist group!” they shouted.

Police were trying to identify the bombers and find out how they managed to target al-Hassan, an important security figure who traveled under great protection and who likely took more precautions following Samaha’s arrest.

“We don’t expect to reveal the crime within few hours,” police commander Maj. Gen. Ashraf Rifi told Future TV. “The investigation is like a puzzle. You collect the pieces and put them together in a logical way.”

Al-Hassan had many potential enemies.

Besides his investigation of Samaha, al-Hassan helped investigate the 2005 assassination of former Lebanese Prime Minister Rafik Hariri, a powerful Sunni figure. An international tribunal indicted four members of Hezbollah for Hariri’s killing, although the group denies involvement.

His department also had a role in breaking up several Israeli spy rings inside Lebanon in recent years, Lebanese officials said.

Al-Hassan, 47, who was married with two children, is expected to be buried Sunday next to Hariri’s tomb in downtown Beirut. His family arrived in Lebanon on Saturday on a private plane from Paris, where they live.

Lebanon’s top Sunni cleric, Grand Mufti Mohammed Rashid Kabbani, condemned the assassination, calling it a “criminal explosion that targets Lebanon and its people.” He also called for self-restraint, saying “the criminal will get his punishment sooner or later.”

But many Lebanese were seething with anger.

In the eastern town of Marj, protesters tried to storm an office of the pro-Syrian Itihad group. Lebanese soldiers pushed them away, wounding five protesters, security officials said. Dozens of people who marched in protest in the border town of Moqueibleh came under fire from the Syrian side of the border, forcing them to disperse, the officials said.

The highway linking central Beirut with the city’s international airport was closed, as well as the highway that links the capital with Syria, the officials said.

In the predominantly Sunni northern city of Tripoli, gunmen were roaming the streets on motorcycles and opening fire in the air.

The army issued a statement urging Lebanese to overcome the crisis and coordinate among themselves in order to give a chance to the “the criminal killers who tried through the crime to incite strife and split the country.”