The Associated Press reports: Thousands of Lebanese civilians and Syrian refugees crammed into cars and pickup trucks fled Monday as Lebanese artillery pounded a border town that had been overrun by militants from neighboring Syria.

The civilian exodus came in the early morning hours during a relative lull in fighting and just a few hours later the bombardment around the town of Arsal had reached an intensity of three shells every minute.

The fighting is the most serious spillover of violence from Syria’s civil war into Lebanon, compounding fears that tiny Lebanon is fast becoming a new front in its neighbor’s conflict, now in its third year. The government has rushed reinforcements to scene, including dozens of armored personal carriers and tanks.