Prison guards across France blocked access to several jails on Tuesday to demand tighter prison security after a prisoner injured three guards last week. /VCG Photo

Christian Ganczarski, a prisoner serving an 18-year sentence at Vendin-le-Vieil prison over the 2002 bombing of a Tunisian synagogue, stabbed three guards on January 11. /VCG Photo

The guards at the Vendin-le-Vieil prison burned tires, wooden pallets and washing machines to block the jail entrance. /VCG Photo

The guards in Fresnes also blocked the way to their prison, locking arms and pushing off anti-riot police to show support to their colleagues in Vendin-le-Vieil. /VCG Photo

Prison officers’ union said the stabbing attack illustrated the lax approach of jail authorities to violent convicts. /VCG Photo