A woman and her son were electrocuted to death while they were trying to save a cow at Kaliganj upazila in Lalmonirhat on Saturday morning.
The cow was also killed on the spot.
The incident took place at Dulali Harikhowa village of Goral union at around 9:00am.
Police and local people said that a cow of the family entered another room of the house where a battery-powered auto-rickshaw was being charged.
At one point, tcow came into contact with a live wire and was electrocuted.
Jamal, the son, rushed to the rescue of the cow and was also electrocuted.
Hearing his screams, his mother Kamala rushed to the scene and tried to save him but was also electrocuted.
Other family members quickly turned the power off, but both Jamal and Kamala had already died on the spot.
Goral PInvestigation Centre chief Mostakim Islam said that Jamal died first while attempting to rescue the cow, while Kamala died while trying to save her son. The family has no complaint about this incident, he added.