The attack took place at a police barracks in the city of al-Arish, the sources said. Authorities suspect the operation was a suicide bombing.
There was no immediate claim of responsibility.
But Islamist militants based in the Sinai have carried out similar attacks that have killed hundreds of soldiers and police since the army toppled Islamist president Mohamed Mursi in 2013 after mass protests against his rule.The violence comes days ahead of an investment conference in the resort of Sharm el-Sheikh that Egypt hopes will project an image of stability and attract billions of dollars.