Patna: A blast inside a house in Taranagar village under Bihta police station area, 40km west of Patna, early on Wednesday, left three persons injured, triggering panic.

Mohammed Pappu, Mohammed Sonu alias Paiju and Pappu's wife Soni sustained injuries in the blast. Police sources said the blast occurred when Pappu and Sonu were making a bomb in the house owned by Sonu. The police detained Pappu, Soni and two others, Khursheed Alam and Khursheed's son Mohammed Arman. Sonu, despite being injured, managed to escape.

Sonu's sister Soni is a government teacher at a primary school in Tarapur.

The impact of the blast was such that the under-construction house was badly damaged. The deafening sound was heard 2km away. Bihta police recovered huge quantity of explosives from the spot.

Bihta police are investigating the case from all possible angles, including involvement of family in criminal activities. The anti-terrorist squad (ATS) and forensic experts are pressed into service. Family members, however, told police the blast took place when they were making crackers.

Patna superintendent of police (SP), Central, D Amarkesh said: "We're probing the case from other possible angles including involvement of family in criminal activities."

Sources said the cracker factory was illegal. "The family did not have a licence to make crackers inside their house," Bihta police SHO Ranjit Kumar Singh said.

"The house where the blast occurred is located in a densely populated area. The injured are undergoing treatment at Bihta referral hospital. We will interrogate them to find out from where they used to get explosives to run the illegal factory."

The blast triggered panic among residents. "The impact was such that the entire village panicked," said Sukhdeo Rai, a resident. "Initially, we thought some LPG cylinder had gone off as many trucks carrying LPG cylinders pass through the route. We later got to know bomb had gone off at Sonu's house. The family has a dubious background as residents have often seen outsiders visiting him late in the evening."

Earlier, the family banked on just a piece of agricultural plot for survival, but in the past few years, their economic condition had improved. They now own bikes, television, fridges and other electronic goods.

The police are looking for Sonu. He alone can say why he had called his brother-in-law Pappu to make bombs as also who supplied explosives for the same.