UTRECHT, Netherlands — Dutch authorities said on Tuesday they were “seriously” investigating a terrorist motive for the Utrecht tram attack because of evidence including a letter found in the suspected gunman’s getaway car.

Police were questioning Turkish-born main suspect Gokmen Tanis, 37, and two other men over Monday’s rampage in which three people were killed and seven injured, three of them seriously.

Dutch Prime Minister Mark Rutte had earlier said they “cannot exclude” other motives including a family dispute, but police and prosecutors on Tuesday said the probe was leaning toward terrorism.

“So far, a terrorist motive is seriously being taken into account. This is based on a letter found in the getaway car among other things and the nature of the facts,” they said in a joint statement.

“Our investigation has established no link between the main suspect and the victims.”

The three people who died in the shooting were a 19-year-old woman from Vianen, south of Utrecht, and two men aged 28 and 49 from Utrecht itself, the statement said.

Armed police captured Tanis after an eight-hour manhunt that virtually shut down the Netherlands’ fourth largest city and saw security stepped up at airports and key sites across the country.

Police said they found a red Renault Clio that the suspect had used as a getaway car after the attack. They had also found a firearm after his arrest.

Tanis and two other men aged 23 and 27 are still being interrogated, police said. Reports said the two other suspects were brothers but unrelated to Tanis.

A stream of mourners laid flowers on Tuesday at the site of the attack near the 24 Oktoberplein square.

“One of the victims was my friend’s girlfriend. So coming here today was the least I could do,” Marco van Rooijen, 43, told AFP.

“I am here to pay homage to the victims and to support their families,” said local resident Yvette Koetjeloozekoot, 29.

Rutte and justice minister Ferd Grapperhaus were to visit Utrecht later on Tuesday to privately meet those caught up in the attack, officials said.

“A day later, I am still filled with horror,” Rutte told parliament.

“There are still many questions about the motive, and the police and prosecutors still have to do a lot of work. But there is no doubt that the impact was huge.”

The attack raised security fears ahead of Wednesday’s provincial elections in which Rutte’s centrist coalition is set to lose seats in the upper house of parliament.

Flags were flying half-mast on many buildings around the Netherlands and on foreign embassies.

Public transport was running again after forensic police finished their investigations at the scene and removed the tram on which the shooting erupted.

But there was also growing anger after it emerged that the suspect had only been freed from jail in a rape case two weeks ago.

Tanis was originally arrested in 2017 then released from pre-trial detention, before being taken back into custody when he breached his bail conditions, the central Netherlands district court said.

He was freed again at the start of March.

In 2014, he was also convicted of “illegal possession of weapons” and attempted theft but acquitted of attempted manslaughter. He was also convicted in recent months for shoplifting and burglary.

Broadcaster NOS meanwhile said some of his relatives had links to fundamentalist groups, but also that he was known for unstable behavior after divorcing his wife two years ago.

A woman involved in the rape case told the Algemeen Dagblad newspaper: “He is completely mad and uses drugs. I have previously warned the police against him. He’s not a terrorist but a psychopath.”

Support for the Netherlands poured in from around the world, including the United States, the EU and Russia.

US Secretary of State Mike Pompeo said: “America stands with you. We will continue to do all we can to help you in this terrible time of tragedy.”

Turkish President Recep Tayyip Erdogan said his country’s intelligence agency was “looking into” the attack.

“Some say it is a family matter, some say it is a terror attack ... Our intelligence agency is looking into the matter”, Erdogan told Ulke TV late Monday. — AFP