UTRECHT, Netherlands: A gunman opened fire on a tram in the Dutch city of Utrecht on Monday (Mar 18), killing three people and injuring nine, said the city's mayor.
Authorities were also working on the basis of it being a terror attack, he added.
"At this stage, we can confirm three deaths and nine wounded, three of them seriously," Utrecht Mayor Jan van Zanen said in a video statement on Twitter.
Armed counter-terrorism police launched a huge manhunt for the attacker, urging local residents in one of the Netherlands' biggest cities to stay indoors in case of further incidents.
Police released a picture of the Turkish-born suspect, naming him as 37-year-old Gokmen Tanis, and warning people not to approach him.
Dutch Prime Minister Mark Rutte said the incident, just days ahead of local elections, was "deeply disturbing" and police stepped up security at mosques and airports.
A body covered in a sheet was seen on the tracks in Utrecht, as armed police and emergency services swarmed the scene, while helicopters hovered overhead.
"We cannot exclude a terrorist motive," the head of the Dutch national counter-terrorism service, Pieter-Jaap Aalbersberg, told a brief news conference before rushing off for a crisis meeting.
Aalbersberg said there had been shooting at "several locations" but did not give further details.
"A major police operation is under way to arrest the gunman," he added.
The terror alert level in Utrecht was raised to maximum level five, he added.
Police later surrounded a building a few hundred metres away, an AFP reporter at the scene said, but it was not clear if the gunman was inside.
The tram shooting happened at around 10.45am local time near the 24 Oktoberplein junction.
One witness told NOS News they had seen an injured person running out of the tram with blood on her hands and clothes who then fell to the ground.
"I brought her into my car and helped her. When the police arrived, she was unconscious," the witness, who was not named, told the broadcaster.
The Utrecht municipality said it advised "everyone to stay indoors until more is known. New incidents are not excluded." The local hospital said it had set up a crisis centre.
Local media showed photographs of masked, armed police and emergency vehicles surrounding a tram that had stopped near a road bridge.
Tram traffic in the area was halted.
Dutch Prime Minister Mark Rutte convened crisis talks, saying he is deeply concerned about the incident.
Mosques in Utrecht had shut for the day following the attack, the ANP news agency said, which comes just days after 50 people were killed at mosques in New Zealand in a rampage by an alleged white supremacist.
All major political parties including Rutte's VVD announced that they were suspending campaigning ahead of Wednesday's local elections which will determine the make-up of the Dutch senate.
An increased police presence could be seen outside the parliament and Rutte's office in The Hague.
Police in the port city of Rotterdam said they had increased security outside mosques.
Utrecht, the Netherlands' fourth largest city with a population of around 340,000, is known for its picturesque canals and large student population. Gun killings are rare in Utrecht, as elsewhere in the Netherlands but there has been a series of recent scares.
In August, a 19-year-old Afghan with a German residence permit stabbed and injured two American tourists at Amsterdam's busy Central Station before being shot and wounded.
In September, Dutch investigators said they had arrested seven people and foiled a "major attack" on civilians at a major event in the Netherlands.
They said they had found a large quantity of bomb-making materials including fertiliser likely to be used in a car bomb.
The men were arrested in the cities of Arnhem and Weert.