Riots erupted after the funeral Sunday for the intelligence chief whose assassination has plunged Lebanon into its worst crisis in years, exposing old grudges and new tensions that threaten to bring the violence engulfing Syria spilling across the border into this tiny and volatile nation.

Hundreds of angry mourners surged toward the offices of the prime minister in downtown Beirut after speakers at the funeral exhorted Sunnis to topple the country’s Hezbollah-led government in revenge for the Friday bomb attack that killed Brig. Gen Wissam al-Hassan, a close ally of Sunni leader Saad Hariri.

Security forces fired tear gas and bullets into the air to hold back the crowd as what had been intended as a peaceful demonstration turned into a display of long-suppressed Sunni rage against the Shiite Hezbollah movement.

Sunni and Christian politicians have blamed Syria for the assassination, accusing President Bashar al-Assad’s regime of targeting Hassan because he exposed a plot allegedly ordered by the Syrian leadership to destabilize Lebanon by planting bombs.

But increasingly their anger is being directed at Hezbollah, as the most powerful force in the alliance running the government and as Syria’s chief Lebanese ally.

“There is no God but God, and Nasrallah is the enemy of God,” chanted some of the thousands of mourners who gathered in downtown Beirut’s Martyrs’ Square for the funeral ceremonies, referring to the Hezbollah leader Hasan Nasrallah in an echo of the Islamic declaration of faith often associated with Sunnis.

By nightfall, most of the demonstrators had dispersed and an uneasy calm settled over the capital as Lebanon braced for what is likely to turn into a prolonged political crisis, echoing the upheaval that consumed the country in the three years after the assassination of Hariri’s father, former prime minister Rafiq Hariri, in 2005.

The potential for the crisis to turn violent was evident in the dark sentiments expressed by some of the Sunnis attending the demonstration.

“Because Shiites are dogs,” said Khaled Hawa, 19, when asked why he had traveled from the northern port of Tripoli for the event. “There will be war in all Lebanon, God willing, because we cannot live like this anymore,” he added.

“Only Sunnis should live in this country. The Shiites should not be here,” said Faisal Abu Azzam, 25, who came from the southern town of Sidon and who vowed to bring the country to a standstill by blocking major roads and burning tires.

“If a Shiite is passing by, we are going to kill them,” added one of his friends, who identified himself as Abu Lahab, 23. “I was born to kill Shiites,” he said proudly.

Anger, but less unity

The mood was in stark contrast to the vast outpouring of nationalistic fervor that erupted following the 2005 assassination of Rafiq Hariri, in a bombing also blamed on Syria. Then, hundreds of thousands of people forced the departure of Syrian troops after 30 years of occupation in a popular uprising dubbed the “Cedar Revolution” because of the emblem on the Lebanese flag that became its symbol.

But although former civil war foes in the Christian, Sunni and Druze communities banded together in an unprecedented display of unity, Shiites stood apart, signaling the emergence of a new sectarian divide that culminated with Hezbollah’s forcible takeover of Sunni West Beirut in 2008 and its eventual control over the government after elections in 2009. None of Lebanon’s main Christian, Sunni or Shiite communities commands a clear majority, locking the country into a longstanding state of shifting sectarian rivalries.

Sunday’s gathering was relatively small, with only a few thousand people showing up in response to the call for a “day of rage” by the opposition March 14 alliance, waving not the Lebanese flag but the emblems of their party and sectarian affiliations.

The same factions that turned out for the 2005 demonstrations also came to mourn Hassan, including the Christian Kataeb and the Lebanese Forces and Hariri’s Sunni Future Movement. They are the dominant groups in the anti-Syrian March 14 alliance, which took its name from the date of the biggest demonstration in 2005.

There were newcomers too, including adherents of the radical Islamist clerics who have emerged in recent years to share leadership of the Sunnis with Hariri, brandishing the black flags emblazoned with the shahadah declaration of faith.

Syrian supporters of the revolt against Assad in Syria were also there, carrying the Syrian revolutionary flag and chanting for the downfall of Assad in a reminder of how closely intertwined the conflicts in Syria and Lebanon have become. “One revolution in two countries,” one of the banners held aloft said.

Sunnis urged to reclaim role

People in the crowd cited disillusionment with the failure of the 2005 demonstrations to transform the balance of power in Lebanon, despite the withdrawal of Syrian troops.

“People became discouraged,” said Tony Jumaa, 50, a Christian who fought with the Lebanese Forces militia in Lebanon’s civil war, explaining the low turnout. Hopes that the 2005 events would enable Lebanese opposed to Syria to reclaim their destiny were dashed by the sectarian violence that ensued and Hezbollah’s ascent to power, he said.

Speakers at Hariri’s funeral urged Sunnis to reclaim their role in the country, spurring the demonstrators to march on the offices of Prime Minister Najib Mikati, a Sunni who is nominally allied with Hezbollah.

“Stop crying like women,” screamed one Sunni cleric over the coffin of Hassan before it was laid to rest beside the body of his friend and benefactor Hariri in a tent alongside the square. “Defend your existence, defend your right in this country. . . . Move!”

Hariri later urged his supporters to go home. “We want to topple this government in a peaceful and democratic way,” he said in a telephone call to his Future TV station.

Ahmed Ramadan and Suzan Haidamous contributed to this report.