Police in Kenya say 42 officers are now known to have been killed in the deadliest attack on police in the country's history.
The officers were chasing suspected cattle rustlers on Saturday when a gun battle broke out in the remote Samburu district.
Some police were airlifted to hospitals in Nairobi for treatment but later died from their injuries.
The ambush happened near Baragoi, in a dry northern region mainly inhabited by nomad communities.
"The officers were in a team pursuing stolen cattle when they were ambushed," the official, who did not wish to be named, said on Saturday.
"Some of the bandits were wounded in the attack and others killed," during the gun battle, he said, but could not give precise numbers.
"Now we fear [police] reprisals because the force that is going to be used to pursue the cattle thieves is not going to be directly only against them and a lot of innocents will suffer," Paul Lenaimadu, a local resident, told AFP news agency.
Cattle theft and the ensuing clashes between rival groups claim dozens of lives every year in Kenya.
Al Jazeera's Peter Greste, reporting from Nairobi: "Although of these conflicts are routed in tribal issues, it appears it is connected to political issues due to the elections taking place in March next year".
"A lot of human rights organisations and observers are getting worried by the increase of violence."
It is rare, however, for police officers themselves to be attacked.
Police numbers there are low and the officers are poorly equipped.
The cattle herders have therefore armed themselves against attacks from rival groups.
The group of rustlers police were pursuing at the time of this latest clash were already suspected of having killed 13 people and wounded three others in a previous raid on October 30.
Elsewhere in Kenya, in the southeast Tana River region, inter-communal violence claimed more than a hundred lives in August and September.
The scale and intensity of those killings - women and children were hacked to death or torched in their huts - shocked many.
Some observers have accused local politicians of stirring up inter-communal hatred for political ends.