More than 100 wives and partners of police have protested in Paris against attacks on police following the killing of an officer on the Champs Elysees.
The Angry Police Wives group marched through the city two days after Xavier Jugele was shot twice in the head by criminal Karim Cheurfi.
Meanwhile French media said a man with a knife had been arrested at the Gare du Nord station. Police have not said if the incident is terrorism-related.
France goes to the polls on Sunday.
Separately, riot police confronted marchers after a trade union demonstration in eastern Paris, which was calling for a "social first round" of voting. Police were pelted with objects and fired tear gas.
Candidates in the presidential election have been accused of exploiting the Champs Elysees attack politically.
The killer had spoken about wanting to kill police but had no apparent link to Islamist radicalism, prosecutors said. A note defending so-called Islamic State (IS) was found near his body.
At the end of the pro-police demonstration, marchers released black balloons signifying police killed in the line of duty and pink balloons for the families they left behind.
Some were carrying placards saying "don't touch my cop", a twist on a well-known French anti-racism slogan.
One placard also said "enough police officers killed and burned", referring not only to Mr Jugele's death but also a firebomb attack on a police car carrying four officers by suspected drug dealers in a poor suburb of Paris last October.
Two of the officers were seriously wounded in the attack
Police officers have also been hurt in recent protests over allegations of police brutality.
Last month three officers were injured in protests after a Chinese man was shot dead by officers. In February protesters attacked a police station amid widespread anger over the alleged rape of a young black man by French police.
Police were also attacked during widespread protests against a controversial labour law last year, with 29 officers injured in one protest in Paris alone.
Who was the victim?
Police officer Xavier Jugelé, 37, was an active campaigner for gay rights, French media report.