German and world leaders condemned on Thursday the deadly shootings in Hanau and pledged to fight against those who try to divide society along ethnic lines.
Speaking Thursday in Berlin, Merkel said "everything will be done to investigate the circumstances of these terrible murders" but that much indicated they were motivated by far-right and racist motives.
In unusually plain words, Merkel said: "Racism is a poison. Hatred is a poison."
Merkel's comments were echoed by Annegret Kramp-Karrenbauer, Germany's defence minister: "It is important to clarify the background now and to lead the political debate, what kind of poison does what we have seen here make in our society?"
A 43-year-old German man shot and killed nine people at several locations in Hanau near Frankfurt overnight in attacks that appear to have been motivated by far-right beliefs, according to officials.
He was later found dead near the body of his 72-year-old mother, said Peter Beuth, the interior minister for the state of Hesse.
Hookah lounges are places where people gather to smoke flavoured tobacco from Middle Eastern water pipes.
The attack was quickly and broadly condemned by many organisations, including the Central Council of Muslims, the Confederation of Kurdish Associations in Germany, and the Central Council of Jews.
Germany's President Frank-Walter Steinmeier said he had reacted with "horror". "I stand on the side of all people who are threatened by acts of racism. They are not alone. The large majority of people in Germany condemn this act and every form of racism, hate and violence," DW quoted him as saying.
Responding to reports that some of the victims may be of Turkish descent, a spokesman for Turkish President Recep Tayyip Erdogan condemned a "racist attack".
"We expect from the German authorities maximum efforts to clear up the incident," Ibrahim Kalin said on Twitter. "Racism is a collective cancer".
EU leaders react
EU chiefs on Thursday expressed shock and sadness after the shootings.
"I am deeply shocked by the tragedy that took place last night in Hanau. My thoughts are with the families and friends of the victims, to whom I want to extend my sincerest condolences. We mourn with you today," European Commission President Ursula von der Leyen, a former German government minister, tweeted.
EU Council head Charles Michel and European Parliament speaker David Sassoli echoed the sentiments in their own tweets.
"The senseless loss of human life is a tragedy -- no matter where it occurs. After the terrible attack our thoughts are with the people in #Hanau. Our heartfelt condolences go to the relatives and friends of the victims," Michel wrote.
Sassoli tweeted: "Shocked and deeply saddened by the horror of the shooting in the German city of #Hanau. Our thoughts go to the victims and their loved ones. We stand united against any form of hatred and violence."