A man was beaten by a mob on Thursday night in Nairobi after he chased his colleague with a knife, as the city records an increase in knife attacks.
The two had disagreed over masonry tools.
Police said Victor Ochieng stabbed Brian Ouma Omondi in the right hand, prompting Mr Omondi to flee from him.
Mr Ochieng then chased after him still carrying the knife.
“His act prompted members of the public who were around to mistake Ochieng as a thief thereby giving him a thorough beating,” police said.
Mr Ochieng suffered multiple injuries and was rushed to Mama Lucy Kibaki Hospital.
The latest incident comes as mugging cases rise in Nairobi.
Many of the muggers are young enough to be in school. They carry crude weapons and gang up on victims.
The thugs walk in groups to attack unsuspecting pedestrians, making away with mobile phones, cash, shoes and other personal valuables. The situation worsens when it rains, at night and on weekends.
On Wednesday, police arrested a 15-year-old boy suspected to be behind a string of armed robberies in the city.
Police said he was arrested after a six-kilometre chase on the Southern Bypass and into Nairobi National Park, into which the boy jumped to try to evade arrest.
The juvenile was arrested by DCI officers on patrol. A knife, which he had allegedly used to stab victims, was seized.
“He led the officers to a spot close to Wilson Airport where they recovered a knife he [used] to stab victims before taking off with their valuables,” a police statement said.
In the city centre, areas around the Kenya National Archives, the Globe Cinema Roundabout, Ronald Ngala Street, River Road and Haile Selassie Avenue are among the most unsafe.
On Friday, newly sworn-in Inspector-General of Police Japhet Koome vowed to address rising insecurity across Kenya now that he is at the helm of the National Police Service (NPS).
Speaking at the Supreme Court grounds moments after taking the oath of office, Mr Koome said he was aware that Kenya has become increasingly insecure in the past few months.
His statements come amid growing public outrage that the NPS is failing Kenyans by not cracking stabbings, shootings and murders that happen in broad daylight.
“I'd like to tell all those crooks that are disturbing the peace by stealing, stabbing and shooting people that this will no longer happen under my watch. I will not sleep on the job,” Mr Koome said.
He warned criminals that the NPS under his administration will do everything to safeguard the lives of Kenyans.
“Let us all enjoy our existence and live peacefully. To the criminals out there, please bear with me because you will face it,” he said.
“We are not threatening anybody but we are stating things as they are. Everybody should earn a living legitimately and not by harassing and stealing from our citizens.
“We urge Kenyans to go about their business; the NPS will protect you and your properties and this is the message I am sending as I take charge of NPS.”