Three bombs exploded in north Sinai on Tuesday, leaving no casualties.
Explosions were heard at a number of sites used by security forces in the city of Al-Arish, including at the police headquarters.
Security sources confirmed to both Ahram Arabic website and Reuter's Aswat Masriya that the explosions were caused by bombs, denying initial reports that suggested that rockets were the cause.
An army committee has looked into the explosions and reported that the bombs were domestically made, Aswat Masriya reported.
Residents at the locations observed heavy smoke after the explosions, while the windows of nearby buildings were shattered.
The Sinai Peninsula has experienced a security vacuum since the 2011 revolution, but militant attacks against security targets have increased dramatically since the overthrow of the Muslim Brotherhood backed-Mohamed Morsi on 3 July.
Both the army and the police have increased their reinforcements in the area to fight what they described as terrorism.
An anti-terrorism operation by the army on Saturday targeted 25 militants, but the military did not specify the numbers of those killed or injured.
Last week, the army announced it arrested 103 "terrorists” and that 60 were killed in its crackdown on terrorism during the period from 5 July to 4 August.