LONDON — Three suspects have been detained in connection to the killing of three people on a tram in the Dutch city of Utrecht on Monday, officials said.

Police said the first suspect was the same man pictured in a photo they had released earlier while warning the public not to approach him. They had identified the man as Gökmen Tanis, 37, who was born in Turkey.

Justice Minister Ferdinand Grapperhaus said authorities were able to identify Tanis from surveillance footage and the getaway car they believed he used to flee the scene. Grapperhaus also said Tanis has a criminal record.

After the his arrest, the threat alert level in Utrecht was lowered to 4. Dutch officials had raised the threat alert to its highest level, 5, after the shooting, which occurred around 10:45 a.m. local time.

Utrecht police announced on its Twitter account that two additional suspects in the attack have been detained, but did not release additional details. Authorities said the update would be the last until Tuesday morning.

Five people were also injured in the attack, and three were in serious condition, authorities said. Mayor Jan van Zanen had previously said that nine people had been hurt, but police later adjusted that number.

“We expect a terror motive. Our thoughts are with the next of kin and the witnesses of this horrific event,” the mayor said.

A prosecutor said at an evening news conference that terrorism could be at play, but investigators also weren't ruling out other motives, including domestic-related.

The police asks you to look out for the 37 year old Gökman Tanis (born in Turkey) associated with the incident this morning at the #24oktoberplein in #Utrecht. Do not approach him but call 0800-6070. pic.twitter.com/U1IWEDtUYu — Politie Utrecht (@PolitieUtrecht) March 18, 2019

Police said earlier they were looking for a least one person who might have fled the scene by car, and didn't exclude the possibility that more people might have been involved. They appealed to the public for any photos taken in the area at the time of the incident.

Just before the shooting, a red Renault Clio was carjacked less than a mile from the scene of the attack and later found elsewhere in the city, police said.

In the wake of the shooting, paramilitary police boosted security at airports and other vital infrastructure. Security was also stepped up at mosques and all trams were stopped. Local schools shut their doors and people were at first advised to stay indoors, but they were later told they could go outside.

Prime Minister Mark Rutte said he was deeply concerned about the incident and convened crisis talks. Minister of Justice Ferdinand Grapperhaus advised the public to stay calm but alert.

King Willem-Alexander and Queen Máxima of the Netherlands said in a statement that "violence like this is unacceptable."

"It hurts us very much that three people have died today and others got hurt," the king and queen said. "Let's stand together for a society where people feel safe, and freedom and tolerance are leading. Our thoughts are with the people of Utrecht."

Utrecht is home to a large student population and is about 25 miles south of Amsterdam. Gun killings are rare in the Netherlands.