Nova Scotia's Department of Justice took the "highly unusual" step Tuesday of offering up to $600,000 for information on four recent killings in the Halifax area.

The province added four homicides to the major unsolved crimes program:

Joseph Cameron, shot dead on March 29 in Dartmouth

Tyler Bradley Richards, shot dead on April 17 in Halifax

Naricho Clayton, shot dead on April 19 in Halifax

Daverico Downey, shot dead on April 23 in North Preston

The program pays up to $150,000 per case for information leading to the arrest and conviction of the killers.

"Adding four homicides to the rewards program at once and within weeks of the homicides occurring is a highly unusual step for investigators, but this is also a highly unusual time for our community," Halifax police Supt. Jim Perrin, who heads the Halifax region's criminal investigation division, said in a news release.

"We are hopeful that the addition of these young men's deaths to the program will prompt someone to come forward and allow us to progress the investigations."

Justice Minister Diana Whalen said people need to "break the code of silence" and call police.

"The recent gun violence in our communities, and the deaths of four young men is tragic," she said in the news release.

"My heart goes out to the families of the victims during this very difficult time, and I want to assure them that myself, the police and our partners are working hard to address this issue."

The program takes tips at 1-888-710-9090. Police say anyone who comes forward with information must provide their name and contact information. They may be called to testify in court. All calls will be recorded.