Police in Mandera town are on a red alert after Al-Shabaab attacked and routed security officers out of Bullahawa, a neigbouring township in Somalia.
At least seven officers of Somalia National Army and 12 civilians were injured in the overnight battle that lasted for over five hours.
Gunfire rent the Mandera town air from 5am to 7am as Kenya police battled to ward off a spillover of the siege on Bullahawa.
The two border towns are separated by a strip of shops and they meet at some point.
The probable frontline was exempted from the boundary Kenya is erecting to stop Al-Shabaab incursion from its war-wracked neighbour.
Seven Somalia National Army (SNA) officers and 12 civilians, including a six-year-old boy, were admitted to private hospitals in Mandera on Monday morning following the clash.
A medical officer at the facility said they suffered gunshot injuries.
"One looks like was injured in an explosion," he told the Nation.
A senior Kenya security official told the Nation that they were hosting most of their Somalia counterparts at Mandera Police Station amid reports that the attackers were planning to advance into Mandera.
The Somalia officers ran for their lives after the heavily armed gunmen took over several security installations within Somalia.
"Their stations have been taken but we are ready just in case the enemy makes advances to our side," said the officer who sought anonymity because he is not authorised to give media briefs.
Kenyan security agencies were spotted taking their positions along the porous border in readiness for any eventuality.
Mandera County Commissioner Frederick Shisia said he would issue a statement later today.
The attack has caused a lot of fear in Mandera town with many shops remaining closed.
Some schools had also not opened as late as 9am. Normally, learning starts at 8am.