Al-Shabaab gunmen killed around 25 Kenyan police on Monday, ambushing some officers in a village in the east of the country after others died when their vehicle hit a landmine planted by the militants.
The Islamist group also burnt five vehicles in the two incidents.
Some 20 police died in the village ambush, which occurred on Monday evening in Yumbis, 45 miles north of the town of Garissa, the 'Standard' and 'Daily Nation' newspapers said.
Police spokesman Masoud Mwinyi confirmed there had been an attack in Yumbis. Other government officials could not immediately be reached for comment.
Al-Shabaab, which has carried out several attacks in Kenya in recent years to try to force Nairobi to withdraw its troops from Somalia, attacked a university in the same area last month and killed 148 people.
The officers were ambushed as they went to assist other police who had been targeted by an explosive device, believed to be a landmine or roadside bomb.
"The area is on the remote side of Garissa not far from the border, that is why we are having a problem getting information instantly," said a police officer based at the county headquarters. "What we know, however, is that several officers have been killed."
Garissa County has remained volatile with numerous attacks since last month when four Al-Shabaab militants stormed Garissa University College, killing 142 students and six security force members during a day-long siege.
The latest attack in Garissa County came just days after extra Kenyan security forces were deployed in the area to strengthen security after a series of raids by gunmen from the Somali-led Al-Qaeda branch.
Also last week, Al-Shabaab militants briefly took control of a mosque in Garissa, delivering a hardline sermon to captive worshippers, before leaving.
Once a Somalia-focused insurgency, Al-Shabaab has in recent years turned its attention to Kenya, demanding it withdraw soldiers that were deployed to Somalia in 2011, and launching a series of attacks, including the 2013 assault on Nairobi's Westgate mall that killed at least 67 people.