Responding to mass shootings, honoring victims, and demanding “common-sense gun reform," volunteers and supporters with the Pennsylvania chapter of Moms Demand Action for Gun Sense in America and Everytown for Gun Safety gathered Sunday at the Philadelphia Episcopal Cathedral in University City.

Originally motivated by the El Paso and Dayton shootings — and reinforced by two consecutive days of mass shootings in Philadelphia — they were joined by more than 100 gun safety rallies in all 50 states.

Organizers called them “recess rallies” to pressure lawmakers to change gun laws in America.

The shootings sparked fresh debate over the nation’s gun laws amid stalemates in Congress and many state legislatures, including Pennsylvania’s.

In Philadelphia, relatives of shooting victims, several community organization representatives, and elected officials spoke, including U.S. Rep. Dwight Evans and state Sen. Sharif Street, who both represent the district where six police officers were shot Wednesday during a 7½-hour standoff in Tioga.

» SPECIAL REPORT: Minute by minute, how a standoff in North Philadelphia left six cops wounded and a city reeling

The groups want Congress to pass legislation requiring background checks on all gun sales and a strong gun violence prevention law, also known as a Red Flag law.

The organizations are also spending more than $1 million on advertising aimed at key Republican senators during the August recess.

“If the president is serious about leading now, then he’ll break with the NRA and tell Majority Leader [Mitch} McConnell to bring the Senate back and pass background checks and Red Flag legislation,” Everytown said in a statement.