A man sat down at a table in a McDonald's restaurant before shooting two men sitting next to him in the Netherlands, according to witness reports.
The alleged gunman reportedly walked into a branch in Zwolle and ordered some food first.
Witnesses said he then sat down at a table and opened fire on two men sat eating next to him.
Panic broke out with other customers - including children - fleeing outside and people comforting each other crying, rtv oost reports.
The area around the McDonald's has been cordoned off and people are being told to stay away, detectives said.
Dutch police said in a statement on Twitter: "We are investigating in Zwolle and are looking for the perpetrator (s) of the shooting incident.
"If you see anything suspicious, call 112 immediately and do not take any action yourself."
Another post by police added: "Two people were killed in the shooting earlier this evening.
"The area surrounding the McDonald's in Zwolle-Noord has been closed as a crime scene for investigation.
"Have you seen anything but haven't spoken to the police yet? Call 0900-8844."
An earlier statement read: "A fatal shooting incident took place at the Floresstraat in Zwolle around 6 p.m. The area has been cordoned off for investigation."
Emergency services are at the scene with reports of officers in bulletproof vests and a police helicopter circling the area.
Police say the identities of the victims must be officially established before they can share the information.
Mayor Peter Snijders of Zwolle said the event has had "a lot of impact on the employees and the visitors present."
He told NOS: "My thoughts are with all those affected and the relatives of the victims and with everyone who was an unsolicited eyewitness."
