France's national police force said Thursday that three officers had been shot dead and a fourth wounded in central France.
The incident took place near the village of Puy-de-Dome during the night into Wednesday.
The officers were shot by a 48-year-old man as they attempted to rescue a woman amid a domestic violence incident.
What happened in Puy-de-Dome?
The woman had allegedly taken refuge on the roof of a house, French broadcaster BFM TV reported.
Police approached the house shortly after midnight and were targeted by gunfire. The gunman initially shot and killed one officer and wounded another, before setting fire to the house.
Two further officers, responding to the scene, were then fired on and killed, according to the Clermont-Ferrand prosecutor's office.
BFM TV named the dead officers as Cyrille Morel, aged 45, Remi Dupuis, aged 37 and Arno Mavel, aged 21.
An ongoing incident
Officials said the woman had been safely rescued. At least seven elite tactical police officers remained on site.
"The greatest precautions are being taken with regard to the dangerousness of the individual," a source close to the investigation told AFP.
Firefighters are at the scene, bringing the blaze under control, according to BFM TV reports.
Investigators are trying to determine whether the gunman died in the house fire or managed to escape, French public broadcaster France Info reported, citing the mayor of Saint-Just, Francois Chautard.
The gunman is said to be known to authorities for charges relating to child custody issues. The operation on Wednesday was related to "intra-family violence," according to news agency AFP.
Politicians offer condolences
France's Prime Minister Jean Castex called the incident "a tragedy" that affects us all and for which the entire country was grieving. He added: "I share the pain of their loved ones and their brothers in arms and assure them of my unwavering support."
France's Interior Minister Gerald Darmanin confirmed the incident via Twitter, adding: The nation bows before their courage and commitment. I offer my condolences to their families and comrades. Every effort is being made to hold the perpetrator to account."
Politician Eric Ciotti, a member of the National Assembly for Alpes-Maritimes, tweeted that there was "immense emotion" following the death of the police officers.
kmm/rt (AFP, Reuters)