French police have two people in custody in connection with four murders outside Paris that authorities fear might be the work of a serial killer, officials said on Saturday.
One was arrested on Saturday afternoon, an official close to the investigation said. He added that police were carrying out searches following the arrest.
Meanwhile, a judicial official said another person was in custody, without specifying when the suspect was brought in. Both officials spoke on condition of anonymity, citing policy.
Prosecutors have said that the same semi-automatic gun was used in all four attacks in the Essonne region and that two victims lived in the same building.
France is on alert after a string of shootings last month in the southwest that police say was the work of an Islamist militant.
That suspect was shot dead in a standoff with security forces.
In the Essonne killings, authorities have stressed there was no evidence of a link to terrorism.
The first victim was killed in November last year. A suspect was detained in that crime, but has since retracted his confession.
The most recent murder was April 5, after which authorities said they were not sure if just one person was behind the killings.