Merkal's statement in full:
This is a very difficult day. I, like millions in Germany, am outraged, shocked and deeply saddened by what happened yesterday in Berlin.
Twelve people who were still with us yesterday, who were looking forward to Christmas and had plans for the holiday, are no longer among us. A horrific and incomprehensible act has robbed them of their lives. More than 40 other people are injured, fighting for their lives or their health.
In these moments I think first of them, the dead and injured and their loved ones. I want them to know that the whole country is united in grief with them. We all hope – and many of us are praying – that they find solace and strength, recover and live on after this dreadful blow.
I think of the emergency services, the police, firefighters, doctors and health workers who served their fellow people yesterday evening in the shadow of the Memorial Church and I thank them from my heart for their difficult work.
I think of the investigators. I have great confidence in the men and women who since yesterday evening have been working to piece together this deplorable act. Every detail of what happened will be uncovered and it will be punished as hard as our law demands.
There is a lot we still don’t know with enough certainty about this act but we must assume it was an act of terrorism.
I know that it would be especially hard for us to bear if someone who had asked for refuge and asylum turned out to have done this. It would be particularly sickening for the many Germans who daily work to help refugees and for those who really do need our shelter and are working to integrate into society.
I’m in constant contact with the president, interior minister De Maiziere and Berlin mayor Michael Muller. In 30 minutes the security cabinet will meet and I have invited the relevant ministers and the heads of the security services to report on the situation and the possible consequences that could arise from it and we will meet again when necessary.
I, along with the mayor and interior minister, will - like so many other Berliners - go to the Breitscheidplatz in the afternoon to express our condolences.
Millions of people, me included, are asking themselves this morning - how can we live with the fact that during a carefree stroll in the Christmas market - a place where we celebrate life - a murderer can cause so many deaths. A simple answer to that, I do not have.
I only know that we cannot and do not wish to give all this up – Christmas markets, good times with family and friends outside in our city squares. We do not want to live paralysed by the fear of evil, even if it is hard in these difficult hours. We will find the strength to live life as we in Germany want to live it – free, with one another and open."