RANCHI: Four Maoist guerrillas were arrested on Tuesday and a small bomb-making factory unearthed in two separate cases in Jharkhand, police said.

Police and the Central Reserve Police Force personnel arrested the four ultras -- Deepak, Jogindra, Chotu and Urmila -- in a joint operation in Palamu district.

The bomb-making factory was unearthed in Pirtand forest in Giridih district on the basis of information given by arrested Maoist commander Sunil Manjhi, who is in a six-day police remand. 

Police seized 103 improvised explosive devices, a lathe, syringes, explosives and chemicals.

Maoists are active in 18 of the 24 districts of the state.