• Three people were killed and five were injured on Monday when at least one gunman opened fire on a tram in Utrecht, in the Netherlands. The authorities called it a possible terrorist attack, and stepped up security at other sites in the Netherlands.
• A manhunt was underway for a Turkish-born man who the Utrecht Police said was “associated with the incident,” and the city’s mayor referred to him as a suspect. It was not clear how many people were involved.
• The Netherlands has been spared the kind of large-scale terrorist attacks that have hit other Western European countries in recent years.
Officials cite the possibility of terrorism
The local police and the national antiterrorism agency said they were looking into the possibility that the shooting, between 10:30 and 11 a.m., was an act of terrorism. Mark Rutte, the prime minister of the Netherlands, said it could not be ruled out.
The mayor of Utrecht, Jan van Zanen, was more definitive. “We are working on the assumption of a terrorist motive,” he said.
The Netherlands’ main counterterrorism agency raised its assessment of the threat in Utrecht Province, just southeast of Amsterdam, to the highest level, and said it had activated a crisis team.
Pieter Jaap Aalbersberg, the national coordinator for antiterrorism and security, said the authorities were debating whether to expand the threat alert to the country as a whole.
The authorities ordered the evacuation of all mosques in Utrecht, and security was increased at mosques elsewhere in the Netherlands.
It was not clear whether those moves stemmed from any specific threat, or whether they were a precaution in the wake of the attacks on two mosques last week in Christchurch, New Zealand, that killed 50 people.
The University Medical Center Utrecht opened a specialized disaster unit in response to the shooting. Mr. van Zanen, the mayor, said three of those injured were seriously hurt.
Mr. Rutte interrupted a weekly cabinet meeting to monitor the situation, and later held a news conference to address it.
A manhunt, a possible suspect, and tightened security
By midafternoon there had been no arrests, despite a heavy police presence across the city.
The Utrecht Police said they were looking for Gokmen Tanis, 37, who was born in Turkey, and posted a security camera image of him online. They did not call him a suspect but said he was “associated with the incident” and warned people not to approach him.
Unlike the police, Mr. van Zanen, the mayor, referred to Mr. Tanis as a suspect.
Local news media quoted witnesses who said there were multiple gunmen involved in the shooting, which took place at 24 October Square, but the police did not comment on the number of attackers.
“We think there is just one perpetrator, but we cannot exclude the possibility of there being several perpetrators,” Mr. van Zanen said.
The police were looking into the carjacking of a red Renault, which was stolen before the attack and then abandoned near the shooting scene. They did not say what connection it might have to the killings.
The Utrecht Police advised people to stay indoors, although that warning was later lifted, and the city’s tram network was shut down in response to the shooting.
The Netherlands has one of the lowest rates of private firearms ownership in Europe, according to international studies, about 2.6 per 100 people, compared to more than one per person in the United States. Its rate of gun homicide, about 0.2 to 0.3 per 100,000 people each year, is fairly typical for Europe, and far below the United States rate of about 4 per 100,000 people.
The attack hit a historic city with a large immigrant population
Utrecht, about 25 miles from Amsterdam, has been a center of Dutch culture and commerce for a millennium. Utrecht University is the largest in the Netherlands, and the city has multiple museums, a medieval old town, canals and the headquarters of the Protestant Church in the Netherlands.
More than 30 percent of the city’s population of about 330,000 is foreign-born, according to the Dutch census.
The attack took place in the Kanaleneiland neighborhood, which is home to a large Muslim community, largely Moroccan and Turkish. It was not clear whether that influenced the decision of the gunman to open fire when and where he did.