A lone gunman opened fire before being killed as he fled the scene, police say. The Champs Elysees was sealed off.
President Francois Hollande said that he was convinced the attack was "terrorist-related".
So-called Islamic State (IS) said that one of its "fighters" had carried out the attack.
Islamist militancy is a major issue in the polls after recent mass attacks claimed by IS, with 238 people killed in jihadist attacks in France since 2015, according to data from AFP news agency.
Several candidates in Sunday's presidential election have ended their campaigns early as a mark of respect.
"On the face of it, the officers were deliberately targeted," interior ministry spokesman Pierre-Henry Brandet said.
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