At least three dead in tram shooting in Dutch city of Utrecht

A gunman killed three people and wounded nine on a streetcar in the Dutch city of Utrecht on Monday morning in what the mayor said appeared to be a terror attack, touching off a manhunt that saw heavily armed officers with dogs zero in on an apartment building nearby.

Authorities immediately raised the terror alert for the area to the highest level, and Dutch military police tightened security at airports and key buildings in the country.

Utrecht Mayor Jan van Zanen said three people were killed and nine 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," van Zanen said.

Dutch Prime Minister Mark Rutte said that "a terror motive is not excluded" and that the attack was met throughout the country with "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.

The shooting took place at a busy intersection in a residential neighborhood. Police erected a white tent over an area where a body appeared to be lying next to the tram.

Anti-terror officers gathered in front of an apartment building close to the scene. A dog wearing a vest with a camera mounted on it was also seen outside the building.

Police spokesman Bernhard Jens said one person might have fled by car, and he did not rule out the possibility that more than one shooter was involved.

The Netherlands' anti-terror coordinator, Pieter-Jaap Aalbersberg, raised the threat alert to its highest level, 5, around Utrecht, a city of nearly 350,000.

Political parties halted campaigning ahead of provincial elections scheduled for Wednesday that will also determine the makeup of Parliament's upper house.

In neighboring Germany, police said they stepped up surveillance of the Dutch border, watching not only major highways but also minor crossings and train routes.

German authorities said they were initially told to look out for a red Renault Clio compact car but were later informed it had been found abandoned in Utrecht.