A gunman killed three people and wounded nine others on a tram in the central Dutch city of Utrecht, sparking a manhunt that saw heavily armed officers with sniffer dogs zero in on an apartment building close to the shooting.
Authorities immediately raised the terror alert for the area to the maximum level, and the city's mayor said a "terror motive" was the most likely theory. Dutch military police went on extra alert at Dutch airports and at key buildings in the country as the Utrecht manhunt took place.
A few hours after the shooting, Utrecht police released a photo of a 37-year-old man born in Turkey who they said was "associated with the incident." The photo showed a bearded man on board a tram, dressed in a dark blue hooded top.
Police warned citizens not to approach the man, whom they identified as Gokmen Tanis, but call authorities instead.
The Utrecht attack came three days after 50 people were killed when an immigrant-hating white nationalist opened fire at two mosques in Christchurch, New Zealand during Friday prayers. There was no immediate indication of any link between the two events.
Police, including heavily armed officers, flooded the area after the shooting Monday morning on a tram at a busy traffic intersection in a residential neighborhood. They later erected a white tent over an area where a body appeared to be lying next to the tram.
Utrecht police said trauma helicopters were sent to the scene and appealed to the public to stay away.
Heavily armed anti-terror officers gathered in front of an apartment building close to the scene. A sniffer dogs wearing a tactical vest with a camera mounted on it was also seen outside the building.
Mayor Jan van Zanen confirmed three deaths and said that nine people were wounded, three of them seriously.
"We cannot exclude, even stronger, we assume a terror motive. Likely there is one attacker, but there could be more," Mr. van Zanen said.
"Our nation was hit by an attack in Utrecht," Dutch Prime Minister Mark Rutte said. He said that "a terror motive is not excluded."
Mr. Rutte said that, throughout the country, "there is a mix of disbelief and disgust."
"If it is a terror attack then we have only one answer: our nation, democracy must be stronger than fanaticism and violence," he added.
Police spokesman Bernhard Jens said one possibility "is that the person fled by car." He did not rule out the possibility that more than one shooter was involved.
The Netherlands' anti-terror coordinator raised the threat alert to its highest level around Utrecht, a city of nearly 350,000 people. Pieter-Jaap Aalbersberg said the "threat level has gone to 5, exclusively for the Utrecht province."
Dutch political parties halted campaigning ahead of provincial elections scheduled for Wednesday that will also determine the makeup of the Dutch parliament's upper house.
In neighboring Germany, police said they had stepped up surveillance of the Dutch border. Heinrich Onstein, a spokesman for federal police in North Rhine-Westphalia state, said additional officers had been detailed to watch not only major highways, but also minor crossings and railway routes.
German authorities were initially told to look out for a red Renault Clio compact sedan, but were later informed it had been found abandoned in Utrecht, Mr. Onstein said.
This story was reported by The Associated Press. Mike Corder reported from The Hague. Raf Casert in Brussels and Geir Moulson and David Rising in Berlin contributed.