Indianapolis ? Thirteen people have been killed in Indianapolis in less than a week – a wave of bloodshed that has alarmed residents and civic leaders and led to stepped-up police patrols in the city’s trouble spots.

Even before the rash of killings stunned the city of about 863,000, Indiana’s capital was already on track for its bloodiest year since 1998, when 162 people died. So far this year, 91 people have been killed in Indianapolis.

Mayor Bart Peterson has called the string of killings since last Wednesday an “extreme emergency” similar to a natural disaster. Six of the slayings took place within 24 hours over the weekend. The latest killing was the stabbing early Tuesday of a 39-year-old man.

The killings have continued even as the Indianapolis police and Marion County Sheriff’s Department have assigned more officers to the streets and extended their shifts by two hours, with some officers working up to 12 hours a day.

Police said there is no common thread to the 13 killings, though they said many of the victims and suspects were young men who grew up in poverty and had messed with guns and drugs.