Toronto police are investigating a string of overnight armed robberies at fast food restaurants and a convenience store downtown.

The first robbery happened in the area of Yonge and Front streets shortly before 9 p.m. on Friday.

Police say a man walked into a fast food restaurant carrying a blunt weapon and took cash from the register. He then fled the scene.

The second robbery occurred shortly after 4:30 a.m. on Saturday in the area of Queen and Beverly streets.

A suspect entered a fast food restaurant with a blunt object and was swinging it around, police say.

"I believe it's a stick or a club or a two-by-four and he would walk into these restaurants or convenience stores," Const. David Hopkinson told CP24. 

He demanded money from everyone and then fled the store.

Shortly before 5 a.m., police received reports about a third incident at Bathurst and Dundas streets.

Police say a suspect entered a fast food restaurant carrying a blunt object and demanded money.

The suspect was confronted by a customer or employee and fled the store without obtaining anything, police say.

The last reported robbery occurred at 5:13 a.m. in the Dundas Street West and Manning Avenue area.

Police say a man entered a convenience store armed with a bunt object and demanded money from employees. He then fled the scene.

Police believe one male suspect is responsible for all four incidents.

"As the night progresses, his behavior becomes more aggressive and he's now swinging the stick and the club at people in the restaurants demanding money not just from the employees, but from the customers and patrons," Hopkinson said. 

No one was injured in any of the incidents.

The suspect is described as white, between 25 and 30 years old, standing at five-foot-six-inches tall, with short dark hair. He was wearing a white t-shirt and off-white pants.

Police say not to approach the suspect but to call 911.