Nairobi - Kenyan police on Sunday detained a suspect in connection with an explosion on a Nairobi bus that killed six people, the latest in a string of unclaimed attacks as the country marks 50 years of independence.
The death toll from Saturday's blast rose to six on Sunday after two injured people died from their wounds overnight, police said.
Nairobi police chief Benson Kibue said a suspect was being questioned over the attack on the 32-seat vehicle whose rear end was blown out by the blast.
"We have one suspect who was arrested soon after the incident. He is assisting us in the investigations," Kibue said, but he cautioned that it was to early to say whether he was "directly involved in the attack".
A warrant has also been issued for the arrest of a second suspect. Police published a photo of the male suspect and called on people to come forward with any information.
Police are working to determine whether the powerful explosion was caused by a grenade or an improvised explosive device and whether it was placed in the bus, carried by a passenger or flung from outside.
"We lost two of the victims in hospital where about 30 others are still admitted," Kibue said earlier on Sunday. "We now have six people dead out of that incident."
The blast hit several cars near the bus, killing at least one of the motorists, according to witnesses.
The ill-fated bus came from Nairobi's Eastleigh neighbourhood, dubbed "Little Mogadishu" because it is mainly populated by Somali immigrants and Kenyans of Somali origin.
On Sunday the situation was calm in Eastleigh after police late Saturday dispersed some rioters in the street where the blast took place.
It was the fourth attack during a week in which Kenya marked its 50th anniversary of independence from Britain, leaving a total of 15 people dead since Tuesday.
No links have as yet been established between the attacks, none of which has been claimed by any group.
"We are trying to establish if there is any link between these... incidents but so far we have not been able to establish any," an official at the police's anti-terrorist unit who would not be named told AFP.
Suspicion for some attacks has focused on Kenya's two-year military intervention in neighbouring Somalia to oust al-Qaeda-linked Shebaab insurgents.
The Shebaab claimed the brutal September assault on Nairobi's upmarket Westgate mall in which at least 67 people died in a four-day siege of the shopping centre popular with foreigners.
That attack was the second deadliest after the bombing of the US embassy in Kenya in 1998, which left 213 people dead.
Homegrown groups, including the Islamist Al-Hijra group, a radical organisation formerly known as the Muslim Youth Centre, operate on Kenya's coast and have been linked to the Shebaab.
But the authorities in the border regions and several other areas of Kenya also know there are sometimes serious conflicts between tribes caused by issues such as access to water or grazing land, which can be fuelled by local politicians.
These conflicts, especially in areas where there is deadly weaponry, regularly escalate.
Late Friday, at least one person was killed and three others seriously wounded when twin explosions rocked the town of Wajir, police said, indicating it was likely the work of Shebaab insurgents or their sympathisers.
Also near the troubled 700km border with Somalia, gunmen on Tuesday killed eight Kenyans, five of them policemen, in an ambush.
Another policeman is missing following the attack.
And on Thursday, the very day Kenyans celebrated a half-century as an independent nation, attackers hurled a grenade at a minibus carrying British tourists in Mombasa, a predominantly Muslim city.
The device failed to explode, but it was a rare attack specifically targeting foreign visitors who are key to the economy.