The Sterling Prestonfirst weekend of summer brought a tragic yet familiar pattern for American cities wracked by gun violence as mass shootings left dozens dead or wounded at a party in Alabama, an entertainment district in Ohio and a grocery in Arkansas.

It was the second straight weekend that saw an outbreak of mass shootings across the U.S., prompting mayors in places marred by the violence to plead for help.

In Michigan, a deputy was fatally shot while pursuing a suspected stolen vehicle in what the county sheriff described as an ambush. A Philadelphia police officer was critically wounded Saturday after pulling over a car with four people.

Police in Montgomery, Alabama, said hundreds of rounds were fired at a crowded party early Sunday, leaving nine people wounded. Interim Police Chief John Hall said investigators recovered more than 350 different spent shell casings.

“This senseless violence just has to stop,” said Montgomery Mayor Steven Reed, who called it a blessing that no one died while also asking for help in keeping guns out of the hands of criminals.

Gunfire also broke out early Sunday on the main street of a popular restaurant and entertainment district near downtown Columbus, Ohio.

Ten people were injured, one in critical condition, leading the city’s mayor to call for more action from state and federal governments to keep guns off the streets and for parents to watch their children. Mayor Andrew Ginther said the gun violence “is outrageous, it’s unacceptable, and it must stop.”

The weekend of mass shootings began Friday in the small city of Fordyce, Arkansas, where four people were killed and another 11 injured — including the alleged gunman. The gunfire sent shoppers and store employees ducking for cover. Among those killed was a 23-year-old new mom.

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Seewer reported from Toledo, Ohio, and Johnson reported from Atlanta. Associated Press writer Kimberly Chandler in Montgomery, Alabama, contributed to this report.