The blast took place when security personnel were dismantling an explosive device in Nasr City on the edge of Cairo, the source said.
An Egyptian police officer was killed on Saturday while attempting to defuse an explosive device found at a church in an eastern Cairo suburb, state television reported, less than two days prior to Coptic Christmas celebrated by Egypt's Christians.
Two policemen and an onlooker were also injured when the device exploded, security sources said.
There was no immediate claim of responsibility for the incident.
Egyptian security forces have stepped up their presence outside churches and other places of worship ahead of New Year's Eve and Coptic Christmas, which is celebrated on January 7.
This is a developing story and will be updated.