African Union military forces also face al-Shabab militants in Mogadishu showdown.
Kenyan aircraft pounded an area held by al-Shabab rebel forces in anticipation of a tough confrontation on the ground, the Associated Press reported Saturday.
Hundreds of civilians fled the area as troops from both sides neared a village in southern Somalia, roughly 70 miles from the Kenyan border.
Kenya unleashed its military against the rebel group six days earlier after a series of cross-border kidnappings. The Somali forces operate with relative impunity within their own famine-stricken country, which has suffered under weak governance for decades.
In separate battles in the capital city of Mogadishu, African Union (AU) forces from Uganda and Burundi fought pitched battles with al-Shabab, which claimed it had killed 70 AU soldiers, a number dismissed by AU authorities as propaganda, according to a dispatch from Reuters.
Al-Shabab has threatened terror attacks on the Kenyan capital of Nairobi in retaliation for the military strike.