Philadelphia finished 2017 with more homicides than it's had since 2012.

315 people had been killed in the city in 2017 as of Monday, according to police. This is a more than 13 percent increase from the same period last year and the highest number since 331 homicides were reported in 2012.

Philadelphia Police Capt. Sekou Kinebrew blamed violence related to the opioid crisis.

"With the increase in demand of these opioids, there's also territorial battles," he said.

Neighborhoods where drugs are sold are the same places where the department is logging many of the killings, Kinebrew said, adding that crews "use violence means to accomplish their economics goals."

"It's a very small minority committing most of the havoc," he said.

The homicide rise does, however, come as Philadelphia is experiencing decreases in reports of shootings, rapes and gun robberies, leading experts to caution against attributing a specific reason to the higher number of killings.

"I don't really think we have a clear sense yet of what could account for increase in deaths relative to trending downward of other crime," said Jordan Hyatt, an assistant professor in the criminology and justice studies department at Drexel University in Philadelphia. He said opioid-related violence could be a reason for the jump but maintained that it's too early to determine a cause.

Kinebrew said the department will have 370 new police officers on the street by September. Having more officers in problem areas will act as a violence deterrent, he said.

Information is also an important tool in preventing deaths, he said. If police know about gang affiliations it can leave them better prepared to predict retaliatory violence between crews and "thwart the next wave of violence," Kinebrew said.