UTRECHT (Netherlands) • A gunman shot dead three people and wounded nine on a tram in the Dutch city of Utrecht yesterday, and police said they were hunting for a 37-year-old Turkish man in an apparent terrorist attack.

The Dutch authorities raised the terrorism threat to its highest level in Utrecht province, schools were told to shut their doors and paramilitary police increased security at airports and other vital infrastructure as well as at mosques.

Prime Minister Mark Rutte convened crisis talks, saying he was deeply concerned about the incident, which came three days after a lone gunman killed 50 people in mass shootings at two mosques in Christchurch, New Zealand.

"The police asks you to watch out for 37-year-old Gokmen Tanis (born in Turkey) in connection with this morning's incident," Dutch police said in a statement.

They issued an image of the man and warned the public not to approach him. They gave no further details.

Utrecht Mayor Jan van Zanen said three people had been killed and nine injured, three of them seriously, in the tram incident.

Mr Rutte said in a statement: "Our country today has been jolted by an attack in Utrecht. Police and prosecutors are looking into what exactly happened. What is known now is that there was shooting at people sitting in a tram in Utrecht."

The Prime Minister did not repeat earlier suggestions that the shooting may have had a terrorist motive.

The Algemeen Dagblad newspaper, citing a witness, said the gunman had targeted one woman on the tram, and then shot other people who had tried to help her.

Dutch television showed counter-terrorism units surrounding a house in Utrecht, but there was no official confirmation that the gunman might be inside.

"A lot is still unclear at this point, and the local authorities are working hard to establish all the facts. What we already know is that a culprit is at large," Counter-Terrorism Agency head Pieter-Jaap Aalbersberg said at a news conference.

Earlier, he said the shooting "appears to be a terrorist attack".

Local broadcaster RTV Utrecht quoted a witness as saying that he had seen a woman lying on the ground amid some kind of confrontation and several men running away from the scene.

A reporter for Dutch broadcaster NOS said a white sheet had been placed over a body near the tram where the shooting had taken place.

Police asked for witnesses to a carjacking that happened near the tram shooting, Sky News reported.

In the tweet, the police said: "Just before the shooting incident on 24 Oktoberplein in Utrecht, a red Renault Clio was captured at the Amerikalaan (a nearby street) during a carjacking. The relevant car was later found on Tichelaarslaan."

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.

The country has been largely spared the kind of attacks which have rocked its closest European neighbours in the past few years, but there has been a series of recent scares.

Last 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.

REUTERS, AGENCE FRANCE-PRESSE