PHILADELPHIA — Philadelphia’s homicide rate is the highest in over a decade, as a particularly violent summer morphed into a deadly fall and the mayor declared gun violence a public health emergency.

As of Dec. 16, 333 people have been victims of homicide in the city, an 11 percent increase from the same period a year ago, and the highest since 2007.

New York and Los Angeles, with populations much larger than Philadelphia’s 1.5 million residents, have had fewer homicides this year. As of Dec. 9, New York City had seen 273 homicides; as of Dec. 8, Los Angeles had 243.

In September, Mayor Jim Kenney ordered his staff to come up with strategies to tackle the crisis like a public health emergency, and their action plan should be ready next month.