A vehicle rigged with an estimated 60 pounds of explosives detonated in Beirut, leaving at least eight people dead and close to 100 injured. Lebanon's former intelligence chief, Brig. Gen. Wissam al-Hassan, was among those killed in Friday's blast.
State Department spokesman Mark Toner said Washington was "concerned" about the situation in Lebanon given the prospects that Syria's civil war could spill over the border. U.S. Secretary of State Hillary Clinton, he added, offered U.S. assistance to the Lebanese government.
"There is going to be an FBI team headed to Lebanon to help with them with their investigation but we'll certainly wait for the results of that investigation," he said.
Friday's bombing brought comparisons to the 2005 explosion that killed former Lebanese Prime Minister Rafik Hariri, a plot thought to involve Syria. Damascus condemned last week's attack as an act of terrorism.
Catherine Ashton, the top foreign policy chief in the European Union, arrived Tuesday in Beirut to meet with Lebanese leaders. The U.N. refugee agency, meanwhile, reports the number of Syrians fleeing the war to Lebanon has topped 100,000 since the conflict began last year.