A cryptic message claiming responsibility for the attack appeared on Twitter from a user with the name "al-Nusra Front in Lebanon." It claimed to be affiliated with the Syrian al Qaeda affiliate with the same name.
MORE: http://www.cnn.com/2014/01/21/world/meast/lebanon-violence/index.html
See also...
At least 4 dead in bomb blast in Lebanon
http://www.cnn.com/2014/02/01/world/meast/lebanon-explosion/index.html
