A van struck four people at the Netherlands' largest music festival in the early hours of Monday, killing one of them and injuring the others before driving off, police said.
Officers said it was not clear whether the van driver had hit the group at the Pinkpop event intentionally or by accident. Later in the morning, officers said they had found the vehicle and arrested a suspect.
The white van struck around 4 am, police said, four hours after the headline act, R&B artist Bruno Mars, had performed in front of 70,000 people.
"This investigation is still underway and we cannot say whether this was something intentional or an accident," said police spokesman Hub Haenen.
Militants have driven vehicles into crowds of people in attacks in London, Berlin, Barcelona and other European cities in recent years.
Pinkpop is held in Landgraaf, a small town near the German and Belgian borders, 220 km southeast of Amsterdam. A sold-out crowd came to see Pearl Jam, the Foo Fighters and others. Mars closed the three-day-festival shortly before midnight.
A police statement said the street where the incident took place, one of two exits from the concert grounds, had been closed for forensic investigation.