Politicians across Germany expressed outrage on Thursday after it emerged that two mayors had been sent threatening emails, just weeks after regional politician Walter Lübcke was killed in what authorities are investigating as a “right-wing exttremist” attack. Police confirmed on Wednesday that Cologne Mayor Henriette Reker received a death threat that they believe was sent by someone active in the right-wing extremist scene.

The case is now being handled by federal prosecutors and investigators in Berlin, as several German politicians have also recently received death threats.

Foreign Minister Heiko Maas condemned the threats and called for better protections for local politicians.

“Death threats against local politicians are disgraceful attempts at intimidation,” Maas told the dpa news agency. “The more disgusting the agitation, the more resolutely we must support all those who are engaged in communities.”

According to local public broadcaster WDR, one of the other politicians targeted was Andreas Hollstein, the mayor of the western town of Altena. Hollstein’s office later confirmed reports of the threats.

Like Reker, Hollstein was also attacked in recent years. In 2017, Altena’s mayor was stabbed by a man in a kebab shop who shouted anti-migrant remarks before slashing the politician’s neck with a knife.

It is not yet clear whether the threats are connected to the shooting of Lübcke, the regional president of Kassel who was killed in early June.

Besides being known for their refugee-friendly stances, both politicians recently spoke out on social media about Lübcke’s death. On Tuesday, Reker wrote on Twitter that his killing “once again makes clear that the enemies of our open society know no boundaries.”