Toronto police have issued a warning about a series of three armed robberies that occurred on Monday in Scarborough.

The first incident happened around 1:30 a.m. when police say a vehicle a woman and man were driving in the Copperwood Square and Port Royal Trail area was rear-ended by a white van.

When they got out of their vehicle to assess the damage, investigators say two men stepped out of the white van with firearms and made demands for the pair's property.

"The man and woman were pushed up against their vehicle and their pockets were searched," a news release said.

While this was happening, one suspect searched the vehicle and obtained their cellphones, a wallet and identification.

The driver of the white van is described as a black man between 18 and 25 years old and was seen carrying an old-model black Glock firearm.

Witness intervened in 2nd incident

Another incident took place nearly 10 kilometres away in North York between 1:15 a.m. and 2:15 a.m. Monday.

According to police, a 20-year-old woman was crossing the street to get to a bus stop at Van Horne Avenue and Don Mills Road when she was nearly struck by a white van that pulled in front of her.

While she was waiting at the bus stop, investigators say, an armed man got out of the white van and demanded she hand over her property.

The two struggled before a witness stepped in causing the suspect to take off in the white van without any items.

Police describe the suspect as a 19-year-old black man who was last seen wearing black pants and carrying a black firearm.

That evening, around 8:45 p.m., another driver was rear-ended by a white van at Burnt Bark Drive and Sanwood Boulevard, near Steeles Avenue East and Kennedy Road.

Man threatened with knife

When the man, 27, stepped out of his vehicle, two men also exited the white van and pretended to assess the damage.

The two men then approached the driver, pushing him to the ground and threatening him with a knife, according to police.

The men made demands for the man's property while a third man got out of the white van and gathered the victim's wallet, cellphone, backpack, car key fob and house keys.

The two suspects that pinned the man to the ground are described by police as black men, between 18 and 25 years old, and wearing dark clothing.

The third suspect is described as a black man, approximately 5-foot 3-inches, and was last seen wearing red clothing.

"Police ask the public to always remain vigilant," a news release said. "If anyone feels they are being followed or are suspicious of a person's activity call 911 immediately."

Anyone with information is asked to call police at 416-808-4200 or Crime Stoppers at 416-222-8477.