Motorcycle gunmen shot dead a police officer and injured three others in Sharqiya on Thursday, the third drive-by shooting in the governorate within 24 hours.
Earlier in the day, two soldiers were wounded when gunmen opened fire on a military barracks in Nile Delta governorate's capital of Zagazig.
On Wednesday, a military officer was badly injured when gunmen on a motorcycle shot him in Sharqiya's Belbeis city.
An Islamist insurgency has killed dozens of policemen and army personnel since the military, prompted by mass protests, ousted Islamist president Mohamed Morsi in July 2013.
Militant activities have long been concentrated in the border Sinai Peninsula but more recently have spread to the Nile Delta and Cairo.
The bombing of a tourist bus earlier this week in southern Sinai, which killed three South Koreans and a local driver, has raised fears of a shift of strategy by militants and is likely to further decimate an already ailing tourism industry.