Armed police were searching multiple buildings in the Dutch city of Utrecht on Monday after a possible terrorist shooting on a tram left at least three people dead and nine injured, some seriously.

“A terrorist motive cannot be excluded” in the incident, which happened at about 10.45am at a tram stop on the city’s central 24 Oktoberplein junction, a police spokesman, Bernhard Jens, told reporters at the scene.

The mayor of Utrecht, Jan van Zanen, said in a video statement that at least three people had died in the attack and nine more were wounded. Dutch media published footage of a body on the ground and reporters said at least 20 people had been admitted to hospital for treatment.

Utrecht police issued a CCTV picture of the suspect, whom they named as Turkish-born Gökmen Tanis, aged 37, and warned people not to approach him themselves but to alert the authorities if they saw him. They also appealed for witness photographs.

 The Dutch prime minister, Mark Rutte, said all efforts were focused on catching the “suspect or suspects” but did not repeat suggestions of a terrorist motive.

“Our country today has been jolted by an attack in Utrecht,” he said. “Police and prosecutors are looking into what exactly happened.”

The national terrorism coordinator told a press conference that a “complex operation” was under way to apprehend what police believed was a single suspect. “Every effort was now being focused” on apprehending the man, Pieter-Jaap Aalbersberg said.

Aalbersberg raised the alert level in Utrecht province to its maximum after the incident. Local schools and colleges were ordered to keep their doors closed until further notice and security was increased in the nearby cities of Amsterdam, Rotterdam and The Hague as well as at Schiphol airport.

The local council advised all Utrecht’s residents to stay indoors if at all possible as the scene of the shooting remained cordoned off and a police anti-terrorism units carried out searches in multiple buildings and apartment blocks in the area.

“Several shots were fired in a tram and several people were injured,” a Utrecht police spokesman, Joost Lanshage, said earlier. “Helicopters are at the scene but no arrests have been made.”

A local broadcaster, RTV Utrecht, quoted a witness named as Jimmy de Koster as saying several shots had been fired. De Koster said he was on his way home from work when he saw a woman lying on the ground next to a tram, shouting: “I have done nothing.”

He said he then heard three shots and saw four men “running fast towards the woman and trying to drag her away”. More gunshots followed and the men ran off, he said, adding: “It was complete and utter chaos.”

The Algemeen Dagblad newspaper reported that the wounded were taken to Utrecht’s main teaching hospital, where a major incident was declared. The newspaper said at least three of the victims had received emergency treatment at the scene.

There were initial reports of shootings in other areas of the city but these were subsequently discounted by police. Other reports claimed at least one man had escaped in a red car, reportedly a Renault Clio.