Three victims were seriously wounded, the station reported.
The assault occurred in Villeurbanne, a suburb of the southeastern city of Lyon, about 4:30 p.m., the station reported.
Emergency services responded to an exit at the Laurent Bonnevay stop of the Lyon Metro.
An official with the Lyon regional administration told that one suspected assailant was detained and at least one other suspect in the attack on Saturday was on the run.
“I am extremely shocked by the attack that has just occurred in the Lyon area during which one person died and several others injured, some seriously,” Lyon mayor Gerard Collomb tweeted.
French authorities have made no official comment about the assault.
Local police unions say it’s too soon to know of any reason to suspect terror.