ANCHORAGE, Alaska (AP) -

A rash of unsolved killings in outdoor public places in Alaska's largest city is putting residents on edge.

Police have urged people to be vigilant and travel in groups at night. But they have released few details on the deaths and say they haven't found any clear links between the cases.

Altogether, the deaths of nine people who were killed on Anchorage trails, parks, and isolated streets since January remain unsolved, among them three cases involving two victims each.

Adding to the feeling of vulnerability, Anchorage has had 25 homicides this year, that's the same number the city had for the entire year in 2015.

Police issued an unusual public advisory this week urging residents to be "extra aware" of their surroundings.