CHICAGO (AP) — Gun violence has marked the unofficial start of summer in Chicago, where dozens have been shot and six have been killed over Memorial Day weekend.

The Chicago Tribune reports a total of 15 people were shot overnight into Tuesday, two fatally. The newspaper says those shootings bring the total number shot since Friday to 68.

Chicago police say final numbers will be released later Tuesday.

Police had announced plans to step up patrols throughout the city in an effort to prevent violence that occurred during Memorial Day weekend last year, when a dozen people were killed and 44 more were hurt.