A police officer and two conscripts were killed in the early hours of Wednesday when gunmen opened fire at a police vehicle in Ismailiya.
Investigations are still ongoing at the scene.
Another police officer was killed in a drive-by shooting in Ismailiya on Tuesday.
There has been a wave of attacks on army and police personnel since the ouster of Islamist president Mohamed Morsi on 3 July 2013.
In late January, an aide to the interior minister was shot dead in a drive-by shooting when he was leaving his home in Giza.
Ismailiya in on the western bank of the Suez Canal in northeastern Egypt.