Local media reported neighbours as saying they were startled by loud shouting.
Police tweeted to say their investigations gave them no reason to suspect a terrorist motive.
One person has been arrested, they added.
A police statement said: “On the Botsaarsstraat there was a fight at 9pm and one man died as a result of a stabbing. The identity of this man is still unknown. The suspect fled.
“Ten minutes later, another stabbing took place on Joseph Postnesstraat. A woman was killed but her identity is not known.
“In this second incident, two people were also injured. They have been transferred to the hospital. The nature of their injuries is unknown. Afterwards, a third injured person was found in a nearby mosque. That person was also transferred to the hospital.
“Research has shown that there is no reason to assume that these incidents have a terrorist motive. The police are still investigating these incidents in the neighbourhood.”
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