Kalonzo Musyoka refused to comment on the attack.
According to police spokesperson Charles Owino, the device thrown at Kalonzo’s residence is a stun hand grenade and it is only used to scare people and not to injure them.
He also said that the police are probing claims of a gun fire after a live bullet was also discovered at the former Vice President’s residence.
"A stun grenade gives you a very loud bang which is meant to scare and not harm," said Owino.
The 2 AM attack on Kalonzo’s Karen residence comes a day after the government withdrew his remaining security detail as he prepared to attend Raila Odinga’s swearing in at Uhuru Park.
NASA co-principal and Bungoma senator Moses Wetangula has termed the attack as an intimidation on opposition chiefs over their strong stand on calls for electoral reforms.
Wetangula called on the government to provide security to leaders and also refuted claims of a possible link to them not showing up at Uhuru Park for the swearing in ceremony.
Kalonzo Musyoka refused to comment on the attack, as opposition leader Raila Odinga is expected to visit his Karen home anytime.