Three Kurdish women have been killed at the Kurdish Information Centre in Paris.
All three were shot in the head.
One of the victims, Sakine Cansiz, is a founder member of the Kurdistan Workers Party, which has waged a 28-year insurgency against the Turkish state.
Kurds in the French capital took to the streets to protest against the killings.
The murders come at a sensitive time as Turkey has recently admitted to holding talks with jailed PKK leader Abdullah Ocalan.
French police have launched a murder investigation involving homicide and anti-terrorism units.
The French Interior Minister, Manuel Valls, who visited the scene said: “Three women have been killed, no doubt murdered. It is completely unacceptable.” He added the killings were “surely an execution”.
Staff members at the centre said the murders were politically motivated.
The bodies were found soon after midnight on Thursday at the Information Centre of Kurdistan, an institute in central Paris with close links to the PKK. According to one Kurdish agency, workers broke in after seeing blood stains at the door.
Any Turkish government contacts with the PKK, deemed a terrorist group by Ankara, Washington and the EU, are also highly controversial in the Turkish political establishment.
Last summer, preceding the move to talks, saw some of the worst bloodshed of the three-decades-old conflict.
The PKK is fighting for greater Kurdish autonomy in the Turkish southeast and many Turks fear such autonomy could stoke demands for an independent Kurdish homeland and undermine Turkey.