The death toll from Nairobi's grenade attack climbed to seven on Monday after one man succumbed to his injuries at Kenyatta National Hospital.
According to the the Kenya Red Cross, four people injured in the blast were discharged on Monday, with 42 still admitted.
Police on Sunday arrested four people in connection with the Saturday night grenade attack at the Machakos country bus station in which six people were killed and 63 injured.
Internal Security Minister George Saitoti said on Sunday initial indications were that the attacks could have been masterminded by Somali terror group Al-Shabaab.
“Obviously we suspect this attack to be linked to Al-Shabaab and we are going to pursue them within and into Somalia,” Prof Saitoti.
Police officers, who talked to the Nation on condition that they are not named because they are not allowed to comment on an ongoing investigation, said among the suspects are Kenyans and foreigners.
Nairobi deputy police boss Moses Ombati could not deny nor confirm the arrests. “We are seriously investigating the matter and that of course involves interrogating some people,” Mr Ombati said.
The sources told Nation the suspects were being questioned by officers from the Anti-Terrorism Police Unit.
Sunday’s grenade attacks follows a posting on Al-Shabaab’s Twitter account last week warning of an impending attack in the country.
The militant group had warned that its fighters had entered Kenya and were planning to strike at strategic installations. (READ: KDF warns of Shabaab threat at borders)
Since Kenya and the Somali Transitional Federal Government launched a joint operation against the Al-Qaeda-linked terrorist group, the militants have staged several attacks in the country.
Prof Saitoti said one person died on the spot while the other five died while undergoing treatment at the Kenyatta National Hospital.
He termed the 7.30pm attack “unfortunate” and said investigations into the incident were ongoing.
“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.
Prof Saitoti, who was addressing a press conference at Harambee House in Nairobi, said he was confident those behind the attack would be brought to justice, noting that those responsible for previous attacks had been caught.
“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 added.
Prof Saitoti said that after the attacks at Kwa Mwaura’s and the Kaka Stage (OTC) in Nairobi, the police successfully apprehended the assailants and recovered explosives.
“Similarly in Mombasa, we were able to pre-empt a number of attempts by such criminals and also recovered several explosives and firearms,” he said.
In January, the militants attacked Gerille town near the Kenya-Somalia border just before 7pm, bombed the Administration Police camp, killed six and abducted three others.
Two of the abductees are still being held hostage.
Since then, the militants have warned they would continue to raid Kenyan towns to kill and abduct.
On Sunday, Prof Saitoti appealed to the public to remain vigilant in identifying and reporting any suspicious characters to the police.
He also urged the public to avoid congregating at the scenes of attacks for their safety and to ensure that the scene is preserved to enable accurate collection of forensic evidence
The government had intensified surveillance at sensitive installations and public places like churches, hotels, shopping malls and bus terminus.
In January, Al-Shabaab released a propaganda video declaring war against Kenya.
The video was released by Sheikh Ahmed Iman Ali, the self-proclaimed leader of Kenyan Al-Shabaab fighters in Somalia.
The report of the UN Somalia and Eritrea Monitoring Group indicates that Sheikh Ali, a former chairman of Muslim Youth Centre in Pumwani, Nairobi, was central in the recruitment of non-Somalis in Nairobi to join Al-Shabaab.
Security has been tightened following reports that Al-Shabaab had sent hit squads to eliminate Defence Minister Yusuf Haji and National Assembly Deputy Speaker Farah Maalim.
Several foreigners including Kenyans have been arrested in the country over links to Al-Shabaab.
Those arrested were either planning to go to war-torn country or had sneaked into Kenya from Somalia.
Many ordinary places have been designated “vital installations” and put under blanket security. Normally, vital installations would include airports, military barracks, police stations and foreign missions.
On Sunday, Vice President Kalonzo Musyoka condemned the attack, terming it cowardly.
He said such attacks would not break the Kenya’s resolve to guarantee security its citizens’ security and vowed that Kenyans will continue to fight terror.
He was speaking at the Kenyatta National Hospital (KNH) where he visited victims and comforted families of those who were injured in the attacks.
He called on Kenyans to remain calm as the security agencies were doing everything possible to bring the culprits to book.
“We will be more committed to fighting terror. We will not allow terrorists any room in our country”, he added.
He commended KNH staff and other rescue agencies for their rapid response in saving the lives of Kenyans.
Planning Assistant minister Peter Kenneth also sent his condolences yesterday to the families of those who perished during the grenade attacks.
He, however, urged the police to ensure safety of Kenyans. “Kenyans on the other hand should pray for our defence forces in Somalia as they fight for our safety,” said Mr Kenneth.