At least 45 al Shabaab militiamen are said to have crossed into the country on Sunday.
According to a leaked intelligence report, the militants entered the country through the border village of Sugrow at around 2pm.
The report adds that the heavily-armed fighters, believed to be members of al Shabaab terror group, have divided themselves into three groups.
"One group of 13 was sighted headed towards Gerille, another towards Konton and another towards Gumarey areas of Wajir East," the information seen by the Star reads in part.
"All officers to be extra alert and take this information seriously."
The Star learned that security organs, including KDF, have been put on high alert.
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The al Shabaab terror group often takes advantage of the long unmanned, porous Kenya-Somalia border to stage attacks in nearby villages.
Wajir county AP county commander Mohamed Sheikh Monday confirmed being privy to the information.
"It is true the gangs have been spotted crossing into Kenya. They are estimated to be around 50," he said
On Friday, another group attacked an ambulance ferrying a pregnant woman to hospital, shattering its windscreen with bullets.
Sheikh said the group had set a barricade near Lafey in Mandera where they replenish their food and supply "without fear".
He accused the military based in camps along the border of doing little to address the situation.
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