A bomb targeted an Egyptian military intelligence building north of Cairo on Sunday, wounding four soldiers, security officials said, in the second bomb attack on the security services in the Nile Delta in less than a week.
The bomb went off near an entrance to the intelligence building in Belbeis, a town 100 km (65 miles) north of Cairo in Sharkiya province. It follows a suicide bomb attack on a police compound in the Nile Delta city of Mansoura on Tuesday that killed 16 people.
An army statement said Sunday's blast had partially destroyed the back wall of the building.
Two security sources described it as an explosive device, while the state-run Nile News TV station said it had been caused by a car bomb.
"We will most probably not have any deaths," one of the security sources said.
It was the latest in a series of attacks that have targeted the security services since the army deposed Islamist President Mohamed Mursi of the Muslim Brotherhood in July.
The government declared the Brotherhood a terrorist organisation following Tuesday's attack, which was condemned by the group and claimed by a radical Islamist faction called Ansar Bayt al-Maqdis.
Five people were also wounded by a bomb that went off near a bus in Cairo on Thursday. That appeared to be the first targeting civilians, though there was no claim of responsibility saying what had been targeted.