A parcel bomb explosion on Thursday at a legal office in central Paris killed a secretary and seriously injured a lawyer, investigators said.
Four other people were hurt in the blast, which went off around midday on the fourth floor of a building in the capital's fashionable eighth arrondissement or district.
The building on Boulevard Malesherbes is where President Nicolas Sarkozy once practised as a lawyer, but there was no suggestion of a link.
Interior Minister Michele Alliot-Marie left Brussels, where she was to attend an EU meeting, in order to visit the scene. In a statement she said she "condemns with the greatest severity this cowardly and hateful act".
The booby-trap was mailed to a law firm run by attorney Catherine Gouet-Jenselme, 60, police said. It was opened by her colleague Olivier Brane, 58, in the presence of his secretary.
Police said there was a second suspect package at the scene which was not opened.
The investigation was being conducted by the anti-terrorist branch of the Paris police.