Nairobi , Kenya ( CNN ) -- A grenade explosion killed seven people and wounded another 24 on Sunday in a predominantly Somali neighborhood of Nairobi , a Kenya Red Cross official said . The grenade was tossed onto a minibus , known as a matatu , full of passengers riding through the Eastleigh section , according to local media reports . No group has claimed responsibility for this attack . Such attacks have escalated since Kenyan forces invaded neighboring Somalia last year to battle the Islamist militant group Al-Shabaab , blaming it for kidnappings of foreigners in the nation . A grenade thrown into a Kenyan church two weeks ago turned a prayer service into carnage , killing one worshipper and wounding 13 others . Witnesses said members of Al-Shabaab were involved , said Nelly Muluka , spokeswoman for the Kenya Red Cross . Seven weeks ago , one child died and several others were hurt in a grenade attack on a children 's Sunday school class in Kenya , the Kenya Red Cross said . Kenyan forces are engaged in a fight in SomalIa to debilitate Al-Shabaab . The group once held large territories in Somalia , but has lost significant ground in the past year , including its southern base of Kismayo , which Kenyan forces took in late September .
A grenade was tossed into a crowded street , local news reports said . No group has claimed responsibility for this attack . Events like this have escalated since Kenyan forces invaded southern Somalia last year .