Kenya faced a new terror threat on Sunday after a grenade attack blamed on Somali Islamist militia killed six people and injured 63 in a bus terminal in the capital Nairobi.
Four grenades were thrown Saturday night only yards apart from a car driving past the busy terminal, Internal Security Minister George Saitoti said Sunday.
Dozens of buses were parked in the terminal packed with Kenyans leaving for the weekend to visit relatives outside the capital.
While responsibility for the attack had not been claimed by late Sunday morning, Kenyan authorities blamed it on the hardline Islamist Shebab militia which Kenyan troops are battling in neighbouring Somalia.
"We suspect this is the work of Al-Shebab, but all this will come out in the investigations," Saitoti told reporters.
Al-Shebab has threatened Kenya since it sent its troops into Somalia in mid-October to dislodge the Islamic insurgents controlling swathes of the south, which it accused of a series of kidnappings and attacks on its territory.
Deploring Saturday's attack, Vice President Kalonzo Musyoka said "This is an act of people who think that they can puncture the resolve to fight terror. It is a difficult moment but it should strengthen our resolve and I am sure we will win."
Two people died on the spot, one on the way to hospital, while three other victims succumbed to their injuries during the night, hospital sources 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," Saitoti said.
Saturday's attack was the deadliest in Nairobi since one in June 2010, not attributed to Islamists, during a public meeting against the adoption of a new constitution, in which the death toll was also six.
Neither attack came close to the devastating Al-Qaeda car bombing of the US embassy in August 1998 that killed 213 people and injured 5,000.
But this latest attack has raised fears of a terror campaign in Nairobi. Less than two weeks after the army sent thousands of troops and tanks into Somalia, two grenade attacks in the space of less than 24 hours at the end of October left one person dead and 30 injured. One grenade was detonated in a bar and the other at a bus stop.
A 28-year-old Kenyan supporter of the Shebab was arrested and jailed for life after admitting carrying out the attacks.
But no further attacks resulted despite the Somali Shebab appealing to their sympathisers to wage a "holy war" on Kenyan soil. The only incidents reported were in northeast Kenya, a poorly patrolled semi-desert region near the border with Somalia.
Internal Security Minister Saitoti gave assurances Sunday that security had been stepped up in response to this latest attack.
"We have intensified security in government installations and all public places, churches, hotels, shopping malls and bus terminuses, so that we may deter such criminals from accomplishing their ill intentions," he said.
Although security had been radically stepped up in recent months near certain luxury hotels, the police presence had been noticeably lower in busy public places like bus stations.