Germany's allies mourned the victims of an apparent truck attack on a central Berlin Christmas market on Tuesday, pledging their support.

"The French share in the mourning of the Germans in the face of this tragedy that has hit all of Europe," French President Francois Hollande said. The French Interior Ministry said it strengthened security measures at its Christmas markets.

At least 12 people died and 48 others were injured when a truck plowed into a Christmas market near the iconic Kaiser Willhelm Memorial Church on Monday evening.

The mayor of Nice, France, said the Berlin Christmas market incident bore similar characteristics to this July's Bastille Day truck attack.

"Same form of attack. Same blind violence. Same hatred of happy people," Nice mayor Philippe Pradal tweeted Tuesday morning. In July, a Tunisian-born man deliberately drove a 19-ton truck into a holiday crowd in the city, killing 86 people.

European Commission President Jean-Claude Juncker said his thoughts were with the families of the victims, saying the news was made even more devastating "because they had gathered there to celebrate the pre-Christmas season, which unites many with peace."

"Grief for the Christmas massacre in Berlin, solidarity with [Chancellor] Angela Merkel and all of the German people," wrote Italian Prime Minister Bernard Gentiloni on Twitter.

Russian President Vladimir Putin sent his condolences to Merkel as well, in a statement on the Kremlin's website. 

"This crime against peaceful citizens is shocking in its savage cynicism," Putin said in the statement.

Authorities in Belgium and the Netherlands are reviewing security measures at their holiday markets following the deadly incident in Germany.

US 'stands at the side of Berlin'

The United States condemned "in the strongest terms what appears to have been a terrorist attack."

"In the fight against all those who ... threaten our societies, we stand at the side of Berlin," White House National Security Council spokesman Ned Price said in a statement. He added that Germany was one of the US' closest allies.

President-elect Donald Trump labeled the incident a "horrifying terror attack," adding that "Islamist terrorists continually slaughter Christians," in a statement. On Twitter, he said "the civilized world must change its thinking."

Trump offered no support for his claim that Islamist terrorists were responsible for the violence.

Christmas markets have a long history in Germany dating back to the Middle Ages. Today they have lost religious significance and are rather popular places to socialize, shop and drink mulled wine in the weeks running up to Christmas.

'A terrible evening for Berlin'

Shortly after news of the incident broke, German Chancellor Angela Merkel said through her spokesman that she mourned those who lost their lives at the Christmas market.

"We are mourning the dead and hope the many people injured can get help," spokesman Steffen Seibert wrote on Twitter.

German President Joachim Gauck called the truck crash "a terrible evening for Berlin and our country."

"I am deeply shaken about the horrible news of what occurred at the memorial church in Berlin," Foreign Minister Frank-Walter Steinmeier said in a statement.

People around the world offered their condolences on social media, tweeting "#PrayforBerlin" and "Ich bin ein Berliner" after the famous speech that US President John F. Kennedy gave in Berlin during the Cold War.

German satirist Jan Böhmermann tweeted "No fear. No hate" and called unity after news of the Christmas market massacre broke.

rs/tj (AP, AFP, dpa, Reuters)