Kenyan men from several ethnic groups in the western town of Moi's Bridge have gone into hiding fearing they will be forcibly circumcised.
This follows the forced circumcision of at least eight men in the small agricultural town by groups of youths from the Bukusu ethnic community.
The Bukusu hold their traditional circumcision ceremonies in August.
But not all of Kenya's communities practise circumcision, which marks the transition from boy to man.
The BBC's Odeo Sirari in Moi's Bridge says the town is dominated by the Bukusu and Kalenjin groups, which practise circumcision, but it is also home to several other groups who do not.
In the last 10 days, Bukusu youths have been rounding up uncircumcised men from other communities such as the Turkana, Teso and Luo groups, he says.
They have been undressing them, smearing mud and dirty water on their bodies and circumcising them by the roadside, sometimes without anaesthetic.
The Bukusu consider an uncircumcised man to be unhygienic and cowardly, but the men from the affected communities are complaining that the Bukusus are imposing their culture on them, our reporter says.
'Sleeping in the bush'
One man told the BBC about his ordeal.
"I was on my way to town when I was ambushed by the rowdy mob", a peanut seller said.
"They took away my bicycle and circumcised me. The following day the police came and took me to hospital. I didn't get adequate medication - they just bandaged me."
Peter Loituktuk, from the Turkana group, told the BBC he and other men were sleeping in the bush to hide from his Bukusu neighbours.
A local Kalenjin chief, Wilson Sirma, said the authorities were concerned such incidents could trigger disharmony in a region that was relatively spared the ethnic violence that engulfed Kenya after the disputed 2007 elections.
But he said he felt the situation was now contained.
Our reporter says some Bukusu have denounced the spate of forced circumcisions.
"We don't force any one from other communities to be circumcised here. If they are doing it, then it is wrong,'' Martin Makongwe told our correspondent at a moonlit circumcision ceremony in nearby Kamukuywa town amid chants from dancing youths.
Another man at the ceremony said: "This a very special occasion for the Bukusu people. It is the time when our boys… become real men."