4-year-old Nagma and 5-year-old Annu Kumari succumbed to AES at the Sri Krishna Medical College and Hospital (SKMCH).
Babul Kumar (4) and Amarjit Kumar (8) also died of the same disease in the private Kejriwal hospital, the sources said.
With these deaths, the toll has mounted to 25 since the outbreak of the disease in May this year, they said.
Meanwhile, Bihar Pradesh Congress Committee (BPCC) president Ashok Chaudhary visited both the hospitals yesterday to enquire about the well-being of the patients.