Strasbourg’s Grand Rabbi Harold-Abraham Weill inspects graves desecrated with swastikas in the Jewish cemetery of Herrlisheim, north of Strasbourg, France, Dec. 14, 2018. Reuters / Vincent Kessler.

French Interior Minister Christophe Castaner on Friday paid his respects at a Jewish cemetery near Strasbourg, days after 37 of its tombstones and a monument to Holocaust victims were defaced with Nazi symbols.

Castaner said the “abject” desecration could have been conducted by a far-right group, but did not elaborate as an investigation was ongoing.

The attack took place hours before a suspected Islamist militant gunman killed four people at a Christmas market in the heart of nearby Strasbourg on Tuesday. Authorities have not linked the two incidents.

Strasbourg reopened its traditional Christmas market under heavy security on Friday, the morning after French police shot dead the gunman suspected of Tuesday evening’s shootings.