The al-Shabaab are to blame for the grenade attack in Nairobi that occurred on Saturday night, Internal Security Minister George Saitoti has said.
"The death toll is now six, and we have 63 people undergoing treatment at the Kenyatta National Hospital, 11 of them were seriously injured," he told reporters. The earlier toll was five dead and around 60 injured.
He said police had launched investigations into the incident. “Such terrorists’ acts on innocent people will not be tolerated and the government will do everything within its power to ensure that security of Kenyans is guaranteed,” he said.
The minister, who was addressing a press conference on Sunday at Harambee House in Nairobi, expressed optimism that the suspects would all be apprehended citing the arrests of those responsible for the successive attacks in Nairobi in October last year.
‘The government assures Kenyans that it will pursue the perpetrators of these acts wherever they are to face the full force of the law," he said.
Prof Saitoti appealed to the members of the public to remain vigilant in identifying and reporting any suspicious characters to the police.
He urged the public to keep away from site of the blast for their own safety and to ensure that the scene is preserved to enable accurate collection of forensic evidence. (SEE IN PICTURES: Explosion rocks Kenyan capital)
He said the Kenyan government had intensified surveillance of public places to deter similar incidences from occurring again.
Kenyan police also condemned the Islamic insurgents and reiterated that the war against terrorism would not be derailed.
"This is a cowardly act by al-Shabaab elements," police spokesman Charles Owino told reporters at the Machakos country bus station, the site of the attack.
"But we will not relent in the war. We will get them and we will continue with the war." Kenya Defence Forces are in Somalia waging war against the al-Shabaab. (READ: KDF warns of Shabaab threat at borders)
A spokesman at the city's main hospital, Kenyatta National Hospital, said at least seven other people were in critical condition following the attack, in which witnesses reported seeing grenades thrown from a moving vehicle.
Vice President Kalonzo Musyoka, while visiting survivors at the hospital, called for calm and reiterated that the al-Shaabab militia would be dealt with. "We urge for calm and we will definitely win the war against terrorism," he said.
This is the deadliest attack in Nairobi since the devastating August 1998 Al-Qaeda bomb attack on the US embassy that killed 213 people and injured 5,000. (READ: CIA agents ‘died in embassy blast’)
Initial reports indicated that three people were killed and over 20 injured but later on Saturday, two others succumbed to their injuries in hospital and the number of those injured confirmed as 59.
A senior police official who did not want to be named told AFP it was believed several grenades had been thrown towards the bus station.
Witness Charles Njenga told AFP: "I just saw a vehicle pass and then someone just threw things that exploded. Many people have been injured."
"I survived because I was in a bus that people were still boarding," he added. Other witnesses spoke of three or four grenades having been thrown in and around the bus station from a moving vehicle.
Traces of blood were still visible at the bus station, where around 10 buses were parked, and ambulances ferrying the wounded to hospital. Others, less seriously injured, were being treated on the spot.
About 500 metres from the bus station, the body of one of the victims, a young man, lay on the ground. "I came to get petrol when I saw a man who was running collapse on the ground," said Reuben Otela, a motorcyclist.
"When I got closer, I saw that he was covered in blood," he added.
It is the first such incident in the Kenyan capital since two grenade attacks carried out within 24 hours of each other in October last year, that killed one person and injured 30 others.
The first of those attacks targeted a bar in the capital; the second was an attack on a bus stop. A Kenyan supporter of Somalia's Islamist al-Shabaab fighters was arrested soon afterwards and convicted after having confessed to the attacks.
No one has so far claimed responsibility for Saturday's killings. But the al-Shabaab have on several occasions threatened reprisal attacks against Kenya since its troops went over the border into southern Somalia in mid-October.
Kenya sent its soldiers, backed by planes and helicopters, into Somalia following the abduction of several foreigners on Kenyan soil -- although the al-Shabaab have denied any involvement in the kidnappings.
A month later, in November, Ethiopian troops and tanks entered Somalia to support the Somali transitional government against the Shabaab.
Earlier on Saturday, al-Shabaab fighters launched a major attack lasting several hours against positions held by Ethiopian forces in southwest Somalia. The battle left many fighters dead, witnesses and military sources on both sides told AFP.
Apart from the Kenyan and Ethiopian forces, the al-Shabaab fighters are under pressure from African Union force of Ugandan and Burundian troops, which has forced them out of the Somali capital Mogadishu.
The Kenyan army has since last month been part of the African Union force.