The dusty border town, which sits close to Ethiopia as well, was thrust into focus last month as Somali troops and allied militia battled the al Qaeda-linked Shabaab group for control of Beledhawo just across the border. The government side gained the town on Saturday.
The regional police boss for North Eastern province confirmed there had been arrests without providing details.
"Our officers have arrested some al Shabaab combatants. A crackdown is still on and the targeted areas of the operation will not be divulged now as it might jeopardise our operation," Leo Nyongesa said by phone.
The source within the force said those arrested included a Pakistani and two Somalis who had acquired citizenship in the United States. Three locals were detained for hosting the suspects, the source added.
They were being flown to Nairobi for further interrogation after being held at the Mandera military camp where they were questioned by the army and police.
Like other nations in the region, Kenya is worried that a four-year old insurgency by al Shabaab against the government in Somalia could breed extremism and spread attacks in the region and beyond.
An African Union peacekeeping force in the capital, Mogadishu, said on Saturday it had captured key positions after heavy fighting that led to an undisclosed number of casualties.
The government launched the offensives in the capital and in the south of the country last month in an attempt to oust the insurgents and return the country to stability after two decades without an effective central government. (M014/K004)