Four teens are facing serious charges in a series of alleged robberies that involved the abduction of victims, and Ottawa police say there could be more victims — suspects.

"These are significant charges. Some of these charges are among the most serious charges in the Criminal Code. When you're starting to talk about robbery, kidnapping and forcible confinement, these are very serious investigations we don't see thankfully that often," robbery unit Staff Sgt. Michael Haarbosch said in an interview Tuesday.

The first incident in July occurred in the parking lot of the South Keys Shopping Centre. (Judy Trinh/CBC News)

The first incident happened July 22 when a boy under the age of 18 arranged to meet someone at the South Keys Shopping Centre, police said in a media release.

When the boy got there he encountered four males instead of one, and they told him to get inside their silver four-door Honda Accord. They then drove around the shopping centre and to various places in Ottawa's south end. The boy was robbed of his phone and cash and was "repeatedly assaulted," police said.

The boy suffered minor injuries and was eventually dropped off "in a secluded commercial area off Rideau Road," police said. He managed to flag down a passing motorist for help.

Boy 'compelled' to rob store

Then, at about 12:15 a.m. on Aug. 3, police responded to a convenience store robbery on Pleasant Park Road off St. Laurent Boulevard. A lone boy armed with a knife, also under the age of 18, had taken cash and cigarettes from a Quickie convenience store and fled to a waiting silver Honda Accord, police said.

As officers began to investigate, the robbery suspect actually called police from the Hunt Club and Hawthorne road area.

The boy said he had been approached by three males in the Honda Accord as he left work in the Findlay Creek area at about 10 p.m. They told him to get inside, then assaulted him with a knife and "eventually compelled him to commit the robbery," police said.

The three males took the cash and cigarettes, then dropped the boy off on Hawthorne Road. He had suffered minor cuts, and police later released him without charges.

Ottawa police have charged a 16-year-old boy in connection with the Aug. 3 robbery of a Quickie convenience store near St. Laurent Boulevard. (Judy Trinh/CBC)

Victim stabbed in leg

Then, between 11 a.m. and 12 p.m. on Aug. 7, a boy under the age of 18 encountered three males parked in a silver Honda Accord near a baseball diamond on Lorry Greenberg Drive.

They then "left the area with him," police said.

The boy was assaulted, choked and stabbed in the leg with a knife, police said. He was also robbed of his phone.

The boy was then dropped off on Bank Street near Queensdale Avenue, and he went to hospital to have his stab wound treated.

Residents who live near the area where the abductions took place said they were shocked.

"I can't even believe that that would happen here. That's horrible," said Christina Barbe as she stood in the parking lot where the first incident occurred.

One young man said he'd think twice about walking in the area with his cellphone in hand.

Arrests, charges

The following day police arrested a 16-year-old boy in connection to the Aug. 3 incident. He's now facing charges connected to all three incidents and is next scheduled to appear in court on Aug. 29.

The charges against him include:

One count of overcoming resistance to an offence by rendering someone unconscious.

Three counts of kidnapping.

Four counts of robbery.

Three counts of conspiracy.

Three counts of forcible confinement.

Two counts of possession of a weapon.

Two counts of breach an undertaking.

Two counts of assault with a weapon.

One count of aggravated assault.

On Aug. 10, police found the Honda Accord and arrested an 18-year-old Ottawa driver they allege was involved in all three incidents. His next court appearance is scheduled for Wednesday.

The charges against him include:

One count of overcoming resistance to an offence by rendering someone unconscious.

Three counts of kidnapping.

Four counts of robbery.

Three counts of conspiracy.

Three counts of forcible confinement.

Two counts of possession of a weapon.

And on Monday, a 14-year-old and a 16-year-old turned themselves in to police at Elgin Street headquarters in connection with the first incident. They are both charged with robbery, kidnapping, forcible confinement and conspiracy.

The 14-year-old is facing other charges including overcoming resistance to an offence by rendering someone unconscious, and breach of probation.

The 14-year-old is scheduled to appear in court Thursday, and the 16-year-old is scheduled to appear Sept. 6.

Could be more suspects, victims

Police are still trying to identify another suspect or suspects connected to the Aug. 3 and Aug. 7 incidents.

"It is currently unclear if it's the same person in each investigation," police said.

"Details may be released at a later date as the investigations continue, and investigators continue to seek and obtain video images from various sources."

Investigators also believe there could be other victims who haven't come forward.

"We've recovered property that we can't account for, specifically cellular phones. So we're somewhat confident that we have other victims out there that probably haven't reported some kind of robbery or theft to police. We're really encouraging people if they haven't reported that to come forward," Haarbosch said.

Anyone involved in similar incidents are asked to call the Ottawa police robbery unit at 613-236-1222, ext. 5116. Anonymous tips can be submitted by calling Crime Stoppers toll-free at 1-800-222-8477 (TIPS).