Paris ? A package bearing homemade bombs blew up Thursday in a lawyer’s office on a tony boulevard in central Paris, killing the woman who opened it. The motive for the unusual attack remained unclear.

The building also housed an unrelated law firm co-founded by President Nicolas Sarkozy, as well as a Holocaust research foundation, although officials said they did not appear to be targeted.

“It is a truly atrocious act,” Sarkozy’s spokesman David Martinon said on France-Info radio.

A messenger delivered the package, a wooden box that turned out to contain two homemade explosive devices, Interior Minister Michele Alliot-Marie said.

The office secretary opened the package and both explosives went off, killing her and seriously injuring a lawyer. Prosecutor Jean-Claude Marin said the secretary had had no reason to suspect anything out of the ordinary.

Anti-terrorist agents were investigating.