By Thomas Mukoya and Ben Makori
NAIROBI (Reuters) - A bomb tore through a minibus in Nairobi's Somali-dominated Eastleigh neighborhood on Sunday, killing six people in an attack highlighting the security risks Kenya faces because of its intervention in Somalia to fight al Qaeda-linked militants.
Kenya has suffered a string of deadly attacks in its capital Nairobi, the port city of Mombasa as well as the eastern garrison town of Garissa over the past year.
The attacks have been blamed on Somali militants and their sympathizers in retaliation for Kenya's deployment of troops in neighboring Somalia last year to drive out al Shabaab rebels whom Nairobi has blamed for attacks on Kenyan territory.
"I saw bodies ripped apart," said a Reuters photographer at the scene of the blast. He saw a crowd lifting five dead bodies wrapped in sacks onto the back of a police vehicle.
The force of the explosion left only the charred skeleton of the minibus, commonly known as matatus in Kenya, the orange seats ripped apart. The windows of a nearby cafe were shattered and two other cars were damaged.
Nairobi regional police commander Moses Ombati said the explosion was caused by a bomb and that there was a possibility it had been inside the matatu when it exploded.
Earlier he said a grenade had been hurled into the matatu.
"It was a bomb that caused the explosion. Five people died on the spot and another died while undergoing treatment at a hospital," he told Reuters.
The Kenya Red Cross said on its Twitter account that seven people had been killed and 24 people had been taken to hospital.
"I just heard a blast. I thought I'd hit something. The van was suddenly thrown upwards," the matatu's driver, Bernard Kibe, told reporters at the scene. He said the matatu had been filled to capacity, with about 25 people onboard.
The attacks in Kenya have intensified since Kenyan troops, alongside African Union forces, launched an offensive seven weeks ago against al Shabaab's last major urban stronghold, the Somali port of Kismayu, forcing the rebels to flee.
"There's a laxity on the side of the government. This is the fourth attack in three weeks," said bystander Maurice Ouma, as a police siren wailed by.
"The government has to take responsibility for providing security for its citizens," he said.
There was no immediate claim of responsibility for the attack but tensions rose in Eastleigh, a Nairobi district often referred to as "Little Mogadishu".
Witnesses reported Kenyan nationals throwing stones at Somalis in Eastleigh, apparently blaming them for the attack, a sentiment shared by Ouma.
"It's unfortunate that now people we're hosting are actually turning against us," he said. Police fired in the air to disperse the crowd.
In September Kenyan police said they seized more than 150 detonators in Nairobi.
In July, masked assailants launched simultaneous gun and grenade attacks on two churches in Garissa, killing at least 17 people.
Armed cattle raiders killed at least 32 Kenyan police officers in a military-style ambush last weekend. The attack exposed how ill-equipped Kenya's police force is as it faces challenges on several fronts, including a presidential election next March.
(Additional reporting Humphrey Malalo; Writing by Yara Bayoumy; Editing by Rosalind Russell)