"This is a difficult day. I am, like millions of people during these hours, horrified and shocked by what happened at the Breitscheidplatz in Berlin," said Merkel, who is vying for her fourth consecutive term as chancellor.
Not everyone in the country sided with Merkel's leadership in the hours after the attack. Most notable among them was Marcus Pretzell, a member of the European Parliament for the Alternative for Germany (AFG), a hard-right, anti-immigration party. He referred to the victims of the tragedy as "Merkel's dead" in a post on Twitter, implying that refugees and immigrants welcomed into the country by Merkel were responsible for the deaths.
Earlier today, a Pakistani man initially detained in connection with the attack was released from custody because of insufficient evidence, the country's federal prosecutor said, increasing the likelihood that other suspects are still at large.
The man, who has not been publicly named, had a pending asylum case. He first entered Germany on Dec. 31, 2015, and arrived in Berlin in February, the country's interior minister said earlier today. He was not on any terrorist watch list and quickly denied involvement in the attack, according to Berlin police.
The terrorist group ISIS has claimed responsibility for the attack, according to the SITE Intel Group, which provides extremist monitoring services to governments, corporations and individuals, according to its website.
The lack of known suspects did not stop Pretzell and other European far-right leaders, such as Geert Wilders, an anti-immigration politician from the Netherlands, from attempting to exploit the tragedy for political gain. Wilders had posted a doctored image on Twitter of Merkel with blood smeared across her hands.
Nationalist, anti-immigration sentiment has been rising throughout the West in recent years, as highlighted by the success of President-elect Donald Trump and the Brexit vote in the U.K. this June.
Merkel has changed her tune on the refugee crisis, adopting a more conservative voice on immigration issues after a wave of terrorist attacks in the summer led to backlash.
Quentin Peel, an associate fellow with the Europe program at Chatham House, a London think tank, spoke to ABC News about the aftermath of the attacks. According to him, a far-right sentiment has been rising throughout the West, but it was unlikely to affect Merkel's election chances in 2017.
"I would expect an incident like this attack to lead to a great coming together of the country for Germany," he said in a phone interview. "Merkel is seen as Germany's steady hand and is mostly regarded a calming influence."
Peel noted that Merkel's support among conservatives has been shaken by groups like the AFG, which he said are strongest in areas of eastern Germany, where economic issues are prominent and immigration has been limited.
He said German leaders were less vulnerable to far-right challengers than other European nations because of the country's comparative economic strength. Referring to the rising popularity in France of the National Front, led by Marine Le Pen, who is known for her staunch anti-immigration views, he said the AFG is considerably weaker and poses less of a threat to Merkel's power.
"Merkel has shown the German people a willingness to face immigration issues," Peel said, citing to her move to the right in recent months. "But she will do it in a tolerant and nonextremist way."