In the wake of mass shootings in El Paso, Texas and Dayton, Ohio, gun policy activists quickly organized a presidential "gun safety" forum in Des Moines Saturday.

Despite Democratic presidential candidates' busy Iowa schedules for this week — with the Iowa State Fair, the Des Moines Register Political Soapbox at the fair, and several other multi-candidate events — 17 said they will attend.Here's what to expect:

The basics

The event starts at 8 a.m. at the Iowa Events Center in downtown Des Moines.

The event was organized by Everytown for Gun Safety Action Fund, Moms Demand Action and Students Demand Action, groups advocating for gun regulation after previous mass shootings throughout the country.

Which candidates will be there

At the forum, the 2020 presidential candidates will talk about their plans to address gun violence. The following candidates are slated to speak at the following times.

U.S. Rep. Tim Ryan, D-Ohio, at 8:05 a.m.

Montana Gov. Steve Bullock at 8:35 a.m.

U.S. Sen. Kirsten Gillibrand, D-New York, at 9 a.m.

South Bend, Indiana Mayor Pete Buttigieg at 9:25 a.m.

U.S. Sen. Amy Klobuchar, D-Minnesota, at 9:50 a.m.

Former Colorado Gov. John Hickenlooper at 10:15 a.m.

Former Housing and Urban Development Secretary Julian Castro at 11:05 a.m.

U.S. Sen. Elizabeth Warren, D-Massachusetts, at 11:30 a.m.

Former New York City Mayor and Everytown founder Michael Bloomberg at noon

Former Vice President Joe Biden at 12:20 p.m.

Former U.S. Rep. Beto O'Rourke, D-Texas, via video message at 12:50 p.m.

U.S. Sen. Bernie Sanders, I-Vermont, at 12:55 p.m.

U.S. Sen. Michael Bennet, D-Colorado, at 1:50 p.m.

U.S. Sen. Kamala Harris, D-California, at 2:15 p.m.

Washington Gov. Jay Inslee at 2:35 p.m.

New York City Mayor Bill de Blasio at 3 p.m.

U.S. Rep. Tulsi Gabbard, D-Hawaii, at 3:25 p.m.

Entrepreneur Andrew Yang at 3:50 p.m.

Some candidates rearranged their schedules to attend — Sanders canceled a planned stop at the Adel Sweet Corn Festival and rescheduled a rural health care town hall to make time for the Everytown forum.

Democratic presidential candidate Beto O'Rourke announced Wednesday that he cancelled his Iowa campaign trip and Iowa State Fair appearance following the mass shooting in El Paso, his hometown. He's scheduled to make an appearance via video at the forum.

How to attend

The event is open to members of the Everytown for Gun Safety Action Fund and members of Moms Demand Action for Gun Sense in America and Students Demand Action for Gun Sense America. People who wish to attend can become members and RSVP here.

More on gun control:

Why the forum was organized

The calls to action from gun policy groups come after two recent mass shootings. Twenty-two people were killed in El Paso after a gunman opened fire Saturday in a Walmart. Ten people were killed in Dayton Sunday by a man who opened fire after leaving a bar in the city's Oregon Historic District.

In Iowa on Wednesday, Biden said President Donald Trump "has fanned the flames of white supremacy." Buttigieg and Inslee both released plans Tuesday to curb gun violence, and several other candidates have expressed their support for Congress to take action: For example, Sanders said he would support an assault rifle ban and Warren said she would take executive action as president to curb gun violence on Twitter.

O'Rourke has criticized Trump for inciting hatred against minority communities, which O'Rourke said leads to mass shootings like the ones in El Paso and Dayton. Trump replied to those remarks by tweeting that O'Rourke should "be quiet!" as Trump prepared to travel to El Paso and Dayton to speak with first-responders and shooting victims Wednesday.

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"El Paso will not be quiet and neither will I," O'Rourke responded on Twitter.

Former New York City Mayor Michael Bloomberg, who founded Everytown in 2006, will also speak at the event. Moms Demand Action and Students Demand Action are Everytown subsidaries.

“The shootings in El Paso and Dayton have rightly outraged Americans, and we are going to make sure that gun safety is front and center in this presidential election — something that is long overdue," Bloomberg said in a news release. He has provided at least $50 million to the groups.

More candidates may join the roster and further details will be announced closer to the event, organizers said in a release.

Robin Opsahl covers political trends for the Register. Reach them at ropsahl@registermedia.com or 515-284-8051. Support reporters who follow your government by becoming a subscriber. Sign up at DesMoinesRegister.com/Deal.