Three suspected Al-Shabaab militants died after an IED they were assembling exploded.
According to police reports, the incident happened at around 4 pm in Fafi, Garissa County.
Four other militants are reported to have sustained serious injuries.
Al-Shabaab militants conduct military drills at a base in Somalia.
Witnesses stated that a Hilux Double Cabin suspected to have originated from the Santaro Al-Shabaab base, picked up the injured militants.
They added that the Double Cabin had Somali registration numbers.
"Be informed that on Thursday, September 10, at about 1600 hours at Fafi Sub-County of Garissa county an IED exploded while being assembled by suspected Al-Shabaab militants.
"The explosion killed three militias on the spot while four others were seriously injured during the explosion," police said in a report filed at Fafi police station.
The incident came almost two months after suspected Al shabaab militants attacked the Korakora Police Station in Garissa county.
Residents stated that more than 20 gunmen staged the attack on the mast before they were repelled by officers manning the site.
North Eastern regional police boss, Rono Bunei, indicated that no police officers were injured during the incident.
There has been a surge of terror-related incidents on the main Kenya-Somali border, with intelligence reports warning that militants have been targeting vital installations.
Trucks carrying Somalia troops with guns.