A van has ploughed into a crowd at Berlin’s annual LGBTQ+ pride parade, killing at least one person and injuring about 15, police said, leading them to call off the event hours after it had begun to protect participants.

Police said those hurt “included several with life-threatening injuries”. They called on everyone to leave the event, one of Europe’s largest LGBTQ+ celebrations, immediately, in a post on X.

The driver of a white van had swerved shortly before 10pm into the Tiergarten park, close to the route of the pride march earlier Saturday, and struck several people on a walking path, police said.

Sirens rang out across the city as authorities said they were looking for the alleged assailant or assailants.

“We are on the scene in the Tiergarten with a large number of police officers and emergency services personnel from the Berlin fire brigade,” they said on X.

“It is believed that a vehicle drove into the Tiergarten, striking and injuring several people. The injured are currently being treated by the emergency services. We are conducting an intensive search for the suspects.”

Emergency services personnel set up a helicopter landing pad near the Reichstag parliament building nearby to transport the injured to hospitals.

Organisers of the parade and rally used social media to call on participants to evacuate the site for their own safety. A message on their Instagram story read in English and German: “Event cancelled” and “Please leave the venue calmly and orderly.”

Participants were advised to head in the direction of the central railway station and away from the Tiergarten.

The German chancellor, Friedrich Merz, vowed to punish the perpetrators. Merz said in a statement that he and the interior minister, Alexander Dobrindt, would “push to make sure this horrific act is fully investigated and punished”.

Hundreds of thousands of people had gathered in the German capital in warm summer sunshine to celebrate the pride parade.

It is known in Germany as Christopher Street Day (CSD), named after the site of the Stonewall Inn in New York City where riots against police raids touched off the modern LGBTQ+ rights movement. CSD was first held in West Berlin in 1979.

Berlin mayor, Kai Wegner, called the deadly assault “an attack on our free and cosmopolitan society” and pledged security authorities would be investigating “with the utmost urgency”.

“Following a peaceful and colourful CSD, the rally for a tolerant and peaceful Berlin was attacked in the most brutal manner,” he said on X. “Berlin is the city of freedom – and our freedom has today been attacked in the most appalling way. My thoughts are with the victims, their families and friends.”

For the first time in its history, CSD began on Friday night this year with a pro-democracy political rally. Berlin will hold a state election in September.

The parade on Saturday ran under the motto “Taking a stand is hot” which organisers said was “in response to increasing hostility” to queer people in Germany.

More than 80 floats and 50 groups on foot joined the procession through the city centre past Potsdamer Platz and the Victory Column monument in the Tiergarten, culminating in a rally at the Brandenburg Gate.

Earlier in the day one person was arrested for resisting police orders at a far-right counterprotest against the event.

Before last year’s pride parade, Berlin LGBTQ+ organisations sounded the alarm that attacks had become more frequent while hard-won rights were under threat.

Campaigners said a rise in hostility has accompanied the surge in support for the far-right Alternative für Deutschland (AfD) party, now the most popular party in national opinion polls, as well as an increase in Islamist-inspired attacks.