BEIRUT: The U.S. Embassy in Lebanon is urging its citizens to exercise caution following a car bomb explosion Friday afternoon in central Beirut that killed Internal Security Forces officer Brig. Gen. Wissam al-Hasan and at least four others.

The embassy noted that the attack has sparked protests throughout Lebanon, including parts of Beirut and Tripoli, with reports of gunfire exchanges between Sunni and Alawite neighborhoods, as well as tire burning.

The email message from the embassy also “reminds U.S. citizens to consult the Department of State’s Travel Warning for Lebanon to exercise caution and take appropriate measures to ensure their safety and security, and to report any suspicious or unusual activity immediately to authorities.”

A massive car bomb exploded in Beirut’s Sassine Square at 2:50 p.m. Friday, killing at least five and wounding 90. It was the largest such attack in central Beirut since former prime minister Rafik Hariri was killed in a car bomb in 2005. Saturday has been designated national day of mourning.