France has fully mobilised its security forces, including elite units, to ensure citizens' protection during this weekend's presidential election, following the fatal shooting of a police officer in central Paris.
Speaking after an emergency meeting of top security officials, Prime Minister Bernard Cazeneuve said all elite units were on top alert for the election to back up the 50,000 police already earmarked for special election duty.
"The Government is fully mobilised," he said in a statement.
"Nothing must be allowed to impede the fundamental democratic process of our country. It falls to us not to give in to fear and intimidation and manipulation which would play into the hands of the enemy."
The first round in France's two-stage election will be held on Sunday, with a second and final round on May 7.
The gunman in the latest attack targeted police guarding the area near the Franklin D Roosevelt metro stop on the Champs Elysees on Thursday night (local time), at the centre of the avenue, which is popular with tourists.
One witness was walking on the pavement nearby when the gunman appeared.
"There was a bus full of police. The man parked just in front of the bus and then he got out a Kalashnikov and then he shot six times," the witness said.
"I thought it was fireworks. Then he hid behind a truck."
Belgium's Interior Minister Jan Jambon, responding to conflicting reports about the gunman's nationality, told the broadcaster VRT the attacker was a French national.
The Islamic State group has claimed responsibility for the attack.
France has lived under a state of emergency since 2015 and has suffered a spate of Islamist militant attacks that have killed more than 230 people in the past two years.
Jihadism and security have been major issues in the tightly fought presidential campaign.
Far-right candidate Marine Le Pen, who has been campaigning on a hard-line anti-immigration platform, said on Friday that France should immediately reinstate border checks and expel foreigners who are on the watch lists of intelligence services.
Map: Map of the location of the Paris shooting