The deceased, Maimuna Hassan, 3, and Rabi Balarabe, 12, lost their lives on Sunday and Monday.
The Jigawa command of the Nigeria Security and Civil Defense Corps (NSCDC) has arrested four suspected armed robbers in the state.
The 45-year-old man said he was kidnapped in Dutse, on Wednesday, along Dutse-Kiyawa road after withdrawing N800,000 from a bank.
The Nigeria Security and Civil Defence Corps (NSCDC) says it nabbed two suspects in Jigawa over possessing 24 bags of adulterated fertiliser.
He said the boy went swimming in a pond in Lelen Kudu village alongside his friends when he drowned.
A five-member fact-finding committee has been tasked to investigate the cause of the explosion and the extent of damage.
Mr Shehu said the incident occurred at about 2:00 p.m. on Tuesday in Majiya town, while the deceased was evacuating sand in a burrow pit.
The inferno caused by the explosion also damaged 17 shops and five houses.
The girls, Maryam Salisu, Bahayura Lawan, and Lawisa Sule, were between the ages of eight and 10 years.
NSCDC boss said the measure was also to ensure protection of critical national assets and infrastructure in the state.