The suspect, who has no fixed abode, will be transferred to a police station for questioning, local police said.
Those hurt, two girls aged 15 and a boy of 13, did not know each other, and no motive has been reported.
All three were released from hospital following treatment.
Police said earlier that they were investigating "several scenarios" and that it was "too early to speculate" about a possible terror motive.
The attack in The Hague came hours after a stabbing in London in which two people were killed and three injured before police shot dead the suspect.
British police say the London attack was a terrorist incident.