BEIRUT — Lebanon’s prime minister on Saturday linked the massive car bomb that tore through Beirut to the civil war in neighboring Syria, the latest signal that the crisis is enflaming an already tense region.

The blast Friday in the heart of Beirut’s Christian area killed eight people, including the country’s intelligence chief, Brig. Gen. Wissam al-Hassan.

The government declared a national day of mourning for the victims on Saturday, but protesters took to the streets, burning tires and setting up roadblocks around the country in a sign of the boiling anger over the bomb.

Lebanese Prime Minister Najib Mikati said Saturday the explosion is linked to al-Hassan’s recent investigation, in which he exposed an alleged plot by Syria to unleash a campaign of bombings and assassinations to sow chaos in Lebanon.

Lebanon’s fractious politics are closely entwined with Syria’s. The countries share a web of political and sectarian ties and rivalries, and Lebanon has been caught up in the fallout of from the civil war pitting Syrian President Bashar Assad’s forces against rebels seeking to overthrow the regime.