CHICAGO (AP) — A shooting at a block party in Detroit left two people dead and more than a dozen wounded, capping a violent holiday weekend in the U.S. that also saw mass shootings in Kentucky and Chicago.

More than 100 people were shot in Chicago, 19 of them fatally, over the long Independence Day weekend, when there is often a spike in violence. One mass shooting Thursday in a neighborhood on Chicago’s South Side, left two women and an 8-year-old boy dead. Two other children were also critically injured.

“We cannot take our eyes off the ball,” Chicago Police Superintendent Larry Snelling said at a Monday news conference. “We cannot stop thinking about the people who have been victimized by this crime.”

City officials announced plans for an emergency resource center to open Monday evening for people struggling with trauma, while Mayor Brandon Johnson blamed the pervasive violence on years of disinvestment and poverty, particularly in the city’s Black neighborhoods. Johnson, who took office last year, said Chicago has not received enough federal resources for victims and that he recently renewed a request for help.

The four-day weekend in Chicago saw a spike in violence compared with the same time period last year when 11 people were killed and more than 60 wounded.

“We are losing a piece of the soul of Chicago,” Johnson said at the news conference. “We will not let criminal activity ruin and harm our city.”

In Detroit, two people were killed and 19 were wounded early Sunday in a shooting at an illegal block party on the city’s east side that was attended by more than 300 people, Detroit Police Chief James White said Monday during a news conference.

Nine weapons and more than 100 shell casings were found at the shooting scene, White said. Fifteen young women and six young men were shot and two of them died — a 20-year-old woman and a 21-year-old man, he said.

“You’ve got a multitude of people that are engaged in this behavior. This isn’t one suspect, one group being targeted. This is a group of people who are essentially engaged in a shootout,” White said.

Asked if Detroit has ever seen so many people injured in a single shooting, White said he wasn’t sure.

White announced Detroit’s new block party strategy, which includes the establishment of a response team that will specialize in making sure residents comply with the rules governing block parties. Police must now treat 911 calls about illegal block parties as “Priority 1” runs.

Mayor Mike Duggan said shootings occurred at six illegal block parties in Detroit over three days starting July 4, leaving 27 people wounded and three dead. He said nearly 40% of the shooting victims lived outside Detroit — some traveled as far as 50 miles (80 kilometers), lured to the parties through social media.

“This is not your neighbor’s family’s party got large. These are intentional pre-planned events looking to attract people from miles away,” Duggan said. “People are coming here carrying illegal weapons, planning to party into the wee hours of the evening believing that the neighbors and the Detroit Police Department will not the stop these lawless gatherings.”

Shootings during the holiday weekend also took place in California and Kentucky, where police say four people were killed and three others wounded in an early morning shooting during a party at a home. The shooting suspect later died after fleeing the home in Florence, Kentucky, and driving into a ditch during a police chase, authorities said. Florence is a city of about 36,000 people located about 12 miles (19 kilometers) south of Cincinnati, Ohio.