"Black powder has been recovered," Senior Superintendent of Police Saket Kumar Singh said after police raided a place at Dhurva in the state capital.
Raids are also being carried out at other places, police sources said.
Additional Director General of Police (Law & Order) S N Pradhan said the accused named by Bihar police hail from Jharkhand.
"Many of the accused in the serial bomb blasts in Patna are from Jharkhand. They might have carried explosives from Jharkhand or might have got from there," he said.
In 2001, two terrorists connected with the American Centre attack in Kolkata were shot dead in Jharkhand's Hazaribagh district.
Today's serial blasts in Patna ahead of Narendra Modi's rally claimed five lives and left 66 persons injured.