A Kenyan military official says soldiers killed four Islamic extremists from Somalia's al-Shabab rebels suspected to have been planning an attack on the coastal county of Lamu.

Military spokesman Col. David Obonyo said Wednesday that Kenyan troops killed the fighters after pursuing them overnight. Obonyo said the extremists launched an exploratory attack on an army base Tuesday. He said a Kenyan soldier was wounded in the gunfight. Obonyo said a cache of weapons was recovered including an improvised bomb.

Somali based al-Shabab militants have killed hundreds of Kenyans since Oct. 2011, when Kenyan troops were deployed to Somalia to fight the rebels. Last week al-Shabab killed five police officers in Mandera County in Kenya's north.