The incident is reported to have happened in the Sagnarigu Municipality of the Northern Region.
The incident happened at around 10:00pm on Tuesday evening, near the Star filling station.
Joy News reports that there were three police officers at the checkpoint, a male and two females, when the robbers attacked.
The gang reportedly gunned down the female officer before stealing weapons belong to the police.
This is the second time in less than three months that armed robbers have attacked police officers at Sagnarigu and stolen their guns.Â