Toronto police have charged eight people in an ongoing investigation dubbed Project Sugar Horse for four homicides and two shootings in the city that date back to 2008.

In a press conference on Thursday, Staff-Insp. Greg McLane of the homicide squad, called the suspects "ruthless" and said they were actively engaged in criminal activities in Toronto.

"It is the belief of investigators and it is alleged that a number of these homicides and shootings are associated to a group of individuals that were active in the City of Toronto," McLane told reporters.

McLane said six search warrants were carried out Thursday morning in the Greater Toronto Area and eight arrests were made in connection to the shootings and homicides.

Toronto police said the homicide victims were: Jermaine Smith, Daniel Davis, Marvin Engelbrecht and Delano Coombs.

Coombs' sister was at the press conference on Thursday. "He's a brother, father, uncle, cousin, nephew," Tricia Rodney said. "I am so grateful for the team that found these people."

Coombs, 27, died of his injuries after he was shot in the chest and face as he drove down an alley in the Dundas Street West and Scarlett Road area in May 2012.

McLane said aside from the deaths of Smith and Coombs, the shootings were "random acts of violence," including a man shot in a schoolyard, and a man shot in the head while walking his dog.

"It's beyond comprehension," McLane said.

McLane said the accused do commit criminal offences together, but he did not refer to them a street gang.

“We can clearly put them with each other,” he said. “They are a group, and they do hang out.”

Also connected to the Project Sugar Horse investigation is the attempted murder of Kenneth Mark, who was approached from behind and shot in the head while speaking with a friend on Sept. 2, 2008 on St. Clair Avenue West.

Police say an unnamed 19-year-old Toronto man has been arrested and charged with the attempted murder. His name cannot be released because he was a youth at the time of the shooting and is charged under the Youth Criminal Justice Act.

Mark, who was reported to be community advocate who worked to chase gangs out of his west-end Toronto neighbourhood, was later shot and killed in a separate shooting incident on Dec. 29, 2009. Police say the 29-year-old had just left a pizza shop when two individuals shot him from behind on Dundas Street near Gilmour Avenue.

Lamar Skeete, 21, was found guilty of first-degree murder in 2012. Two other men, who were both 16 at the time of the shooting, were also charged with first-degree murder.

McLane said the arrests are one phase in the investigation, and police continue to look for information about the accuseds, who range in age from 19 to 29.