Authorities seized a Turkish-born suspect after a manhunt that convulsed the historic city of nearly 350,000 people for most of Monday.
As night set in, three victims lay in critical condition, and the motive for the bloodshed remained under investigation.
Prime Minister Mark Rutte said authorities were trying to determine whether the attack had "terror motives."
Justice Minister Ferd Grapperhaus said the suspect, identified as Gokmen Tanis (37), was known to justice authorities and had a criminal record, but would not elaborate. Police said they also detained another man on suspicion of involvement but released no details.
The shooting came three days after 50 people were killed and dozens more injured when an Australian-born immigrant-hating white supremacist in New Zealand opened fire at two mosques in Christchurch during Friday prayers. There was no immediate indication of any link between the two events.
"We assume a terror motive," Mayor Jan van Zanen said as police searched for the killer, though he added that other motives could not be ruled out.
In the aftermath of the shooting, Dutch authorities put the Netherlands' fourth-largest city on lockdown, raised the threat level in the area to the maximum of 5 and tightened security at airports and key buildings in the country. Police issued a photo of a bearded Tanis aboard a tram in a blue hooded top.
"If it is a terror attack," Rutte declared, "then we have only one answer: Our nation, democracy, must be stronger that fanaticism and violence."
Heavily armed officers with dogs searched for the killer, gathering at one point in front of an apartment building close to the scene. However, the suspect was later arrested at another location in the city. The threat level soon returned to 4.
Police said a red Renault compact car was carjacked shortly before the shooting and later found across town.
Local media said Tanis had been charged several times over the past years with offenses ranging from attempted manslaughter to petty crime in and around Utrecht. Two weeks ago he was in court on charges of raping of woman in 2017, news reports said.
The identities of the shooting victims were not immediately released, and Grapperhaus would not say if any were known to the gunman.
Political parties halted campaigning ahead of provincial elections scheduled for Wednesday that will also determine the make-up of Parliament's upper house. A televised debate also was cancelled. It was not clear if campaigning would resume on Tuesday.
