On Monday, former New York City Mayor and 2020 Democratic presidential candidate Michael Bloomberg tweeted out a wildly misleading campaign ad.

Above the video, Bloomberg wrote: “21 students are shot every day – because of Trump’s unwillingness to act. Between protecting the NRA and our children, he’s made his choice. Which is why we need to beat him.”

The video, which was uploaded to YouTube on Tuesday, features various clips of President Trump speaking about gun safety before on-screen text reads: “Here’s every school shooting since Trump took office.”

The video then lists hundreds of “school shootings,” eventually reaching the number 263.

Here’s the problem – “school shooting” is a subjective phrase with no commonly understood objective definition. What this means in practice is that any time a firearm is discharged at or near a school, it can be labeled a “school shooting.”

One could argue that in the minds of many Americans, a “school shooting” is a mass-casualty incident in which one or more active shooters open fire in a school with the express and singular intent of killing as many innocent people as possible.

This widespread definitional perception of “school shooting” could be the result of the way in which the media covers mass-casualty shootings at high schools and universities such as Columbine, Virginia Tech, and Parkland.

Regardless, because of this perception, there will be some who see Bloomberg’s video and come to the conclusion that there have been 263 mass-casualty shootings at schools and universities since President Trump came into office.

This is not true.

Among the “school shootings” listed in Bloomberg’s video are multiple suicides (at least one of which just happened to take place in a school parking lot) and unintentional firearm discharges. A mass-casualty event like the May 2018 Santa Fe High School shooting in which ten people were murdered is listed alongside these other incidents as though in the same vein.

Here are some of the “school shootings” in the Bloomberg list:

In February 2017, a man allegedly kidnapped his former girlfriend, and drove her to a parking lot at Maplewood Middle School in St. Paul, Minnesota. When she escaped from the vehicle, he proceeded to shoot himself in the head, reports Star Tribune.

In May 2018, one woman was injured and another killed following a verbal confrontation that turned violent in a parking lot at Mount Zion High School in Jonesboro, Georgia, according to AJC.

In September 2018, a student at Appling County High School in Baxley, Georgia, was found in a restroom with a gunshot wound, reports WSAV. He later died.

In November 2018, a school resource officer committed suicide by firearm while in his office at Eastern Technical High School in Baltimore, Maryland, according to The Baltimore Sun.

In December 2018, a student at Jefferson High School in Jefferson, Oregon, reportedly took his own life using a firearm, according to the Albany Democrat-Herald.

In March 2019, police confronted a man who was reported to have been sleeping in the Fine Arts building at the University of Wisconsin-Milwaukee. Police engaged the man, who was allegedly carrying a weapon. The physical altercation ended when police shot and killed the man, reports FOX6.

In August 2019, “a man allegedly fired at least three shots into the ground” on the football field at Roosevelt High School in Long Island, New York, during “a dispute with landscapers over trees that had fallen across his property line,” according to WABC.

In August 2019, a student at Hollenbeck Middle School was hit with what appears to have been a stray bullet. School Police Chief Steven Zipperman claims no students or faculty noticed anything out of the ordinary at the time of the incident. The principal of the school later noted that the bullet came from “off-campus,” reports FOX11.

In October 2019, a student at the University of Georgia shot himself in the leg by accident with a firearm, according to college newspaper The Red and Black.

The incidents above are listed in the video alongside mass-casualty shootings. It appears likely that Bloomberg is getting his information from Everytown for Gun Safety – an organization he founded.

[In the video, the “shootings” appear just as school names. Not definitively knowing the source of Bloomberg’s information, I used a search engine to cross-reference the school names with news articles pertaining to shootings.]

Democratic candidate Andrew Yang made a similarly misleading gun crimes claim in August when he released his plan to combat gun violence.

In the plan, it states:

Gun violence is a scourge in this country. … After the tragedies in El Paso and Dayton, there have been 255 mass shootings in 2019 – more than days have passed in the year. Our children are twice as likely to die from gun violence than cancer.

As The Daily Wire previously reported, Yang didn’t cite the source from which he obtained his information, however, the data line up identically with those of the Gun Violence Archive (GVA).

GVA’s criteria for what constitutes a mass shooting is different than what is established by an organization like Mother Jones, which has a stricter set of guidelines.

According to GVA:

GVA uses a purely statistical threshold to define mass shooting based ONLY on the numeric value of 4 or more shot or killed, not including the shooter. GVA does not parse the definition to remove any subcategory of shooting. To that end we don’t exclude, set apart, caveat, or differentiate victims based upon the circumstances in which they were shot. GVA believes that equal importance is given to the counting of those injured as well as killed in a mass shooting incident.

Mother Jones, which has one of the most comprehensive data sets on mass shootings available online, has a different set of criteria.

“Dating back to at least 2005, the FBI and leading criminologists essentially defined a mass shooting as a single attack in a public place in which four or more victims were killed. We adopted that baseline for fatalities when we gathered data in 2012 on three decades worth of cases,” states the website.

“In January 2013, a mandate for federal investigation of mass shootings authorized by President Barack Obama lowered that baseline to three or more victims killed. Accordingly, we include attacks dating from January 2013 in which three or more victims were killed,” Mother Jones continues, adding that their estimate may appear conservative because they don’t include shootings that result in fewer fatalities.

As a result of Yang’s usage of the GVA data without citation and explanation, his message about mass shootings is, intentionally or not, misleading.