Fighting continued for the second day May 21 between the Lebanese army and the Syrian-backed Fatah al-Islam movement in the Nahr al-Bared Palestinian refugee camp in northern Lebanon. The catalyst for this standoff was the raid by Lebanese security forces early May 20 on a suspected Fatah al-Islam safe-house in the northern Lebanese city of Tripoli. The government forces were pursuing suspects involved in a May 19 bank robbery in Amioun, where armed men stole more than $100,000. Lebanese security forces thought they were conducting a limited operation against a Fatah al-Islam hideout, but the situation soon spiraled out of the control when the militants responded by attacking army checkpoints in the north. Security sources in Lebanon say that lack of intelligence, combined with poor coordination between the army and internal security forces, led to an unforeseen massacre.