Mosques in the Dutch city of Utrecht were evacuated and locked down after a gunman open-fired on a tram, killing three people and injuring five others.
He then went on the run for seven hours, before being apprehended by armed police.
There's no link to the Christchurch attack as yet, but authorities didn't take any chances, immediately raising the terror threat level to the highest possible.
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Counter-terror officers rushed to the tram in downtown Utrecht where a man had fired on eight passengers.
While detectives secured the scene, erecting tents over the victims, a hunt began for 37-year-old Turkish-born suspect Gokmen Tanis.
CCTV camera on the tram that would soon become his crime scene captured footage of the scene.
Authorities didn't know if the gunman was acting alone or if it was part of a larger, coordinated attack, but given what's happened in Christchurch, they were on high alert.
Prime Minister Mark Rutte says a terrorist motive cannot be excluded, adding that the information police has is mixed.
"We are horrified and in disbelief," he says, "this has hit people in the Netherlands very hard."
Specialist forces spent seven hours searching for the suspect, storming local buildings, cordoning off a vast area, and even searching from the air.
Schools went into lock down, as did mosques and the central train station, and there was an increased presence of armed police at Schipol airport.
Then just before nightfall, officers captured their suspect.
It's since emerged the suspect was known to police, and it's understood his previous charges have included rape, attempted manslaughter, and petty crimes.
After today, that list of charges will no doubt grow, as Utrecht recovers from its day of terror.