"I was across the hall at another hearing, and so that is why I came in late, and the reason I came over here was because I got a text to me, saying that right now, as we sit here, there is an active shooter in my part of the state of Illinois, in Rockford, Illinois," Bustos said.

The irony was not lost on Bustos as lawmakers gathered Thursday for a hearing about gun violence research. With rates of gun deaths appearing to rise , the issue has been called a public health emergency.

The room fell quiet as Bustos described how the shooter was being served a warrant before he opened fire and shot a law enforcement officer. Rockford Police said the suspect, 39-year-old Floyd Brown , was accused of shooting an agent with the US Marshals task force.

"This shooter is now on the loose, so everybody in our community is being warned about how he is armed and dangerous," Bustos told the room.

"Everybody sitting up here, everybody sitting out there knows of these kind of stories, and just the imminent threat, and you just never know when these things are going to hit," she said. "I just can not imagine the fact that the Centers for Disease Control and Prevention hasn't invested more resources to get to the bottom of this. ... This is really hitting home right now."

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federal funding for gun violence prevention research as Congress enters the 2020 fiscal year appropriations process. The House Appropriations Committee's Labor, Health and Human Services, Education, and Related Agencies Appropriations Subcommittee held the hearing to address potentialfederal funding for gun violence prevention research as Congress enters the 2020 fiscal year appropriations process.

The idea is that more research could help better inform the nation's understanding of gun violence as well as the decision-making around possible legislation.

"Nearly 40,000 Americans are killed by guns each year, and tens of thousands more are treated for gun injuries," New York Congresswoman Nita Lowey, who chairs the House Appropriations Committee, said in a news release ahead of the hearing

"It is clear that the United States faces a public health emergency of gun violence, one that is breaking apart families, eroding the safety of communities, and threatening our shared future," she said. "Only by conducting scientific research on gun violence can we better understand the causes of this crisis and develop and implement a public health response to reduce gun injuries and deaths."

Lowey said that without dedicated funding from Congress, the US Centers for Disease Control and Prevention "cannot move forward with the important work of performing research into the causes of gun violence."

prepared The American College of Surgeons "supports an appropriations request of $50 million specifically for firearm morbidity and mortality prevention research through the CDC" as part of the 2020 fiscal year, Dr. Ronald Stewart, director of trauma programs at the American College of Surgeons Committee on Trauma, said in aprepared statement for delivery to lawmakers at the hearing

Why a debate over funding gun violence research rages on

Ahead of that vote, Democrats pushed for federal government funding to conduct gun violence research. Republicans argued that such research was never prevented in the first place. The Dickey Amendment, named after the late Republican Rep. Jay Dickey of Arkansas, sits at the heart of that tension.

The amendment passed in 1996 when Congress removed $2.6 million -- which is the amount the CDC spent on gun research during the prior year -- from the CDC's budget for fiscal year 1997. The amendment stated that "none of the funds made available for injury prevention and control at the Centers for Disease Control and Prevention may be used to advocate or promote gun control."

While this language does not explicitly ban research on gun violence, the CDC's previous investment of $2.6 million into firearm injury research was redistributed to study traumatic brain injury prevention.

So while the CDC commonly shifts budget priorities, ever since the mid-1990s, some scientists saw the Dickey Amendment as a way to "silence" the science of gun research.

More recently, amid a wave of mass shootings over the past decade, Democrats have been calling for a full repeal of the Dickey Amendment to give a clear go-ahead to the CDC to resume research.

Then, there are some experts "who have suggested that dedicated research funding is not inconsistent with retaining the Dickey Amendment," Andrew Morral, a senior behavioral scientist at the RAND Corporation, said in Thursday's hearing.

He mentioned how Dr. Victor Dzau, the president of the National Academy of Medicine, and Mark Rosenberg, who led the CDC's injury prevention center at the time the Dickey Amendment was first introduced, have argued that the amendment should be retained as a "guardrail" for managing a federal firearms research program, "but that we have dedicated research funding and appropriation for firearm violence research so that we can do the non-policy-advocacy research."

The National Rifle Association has long supported the Dickey Amendment.

"The Dickey Amendment has never restricted the Centers for Disease Control and Prevention from studying firearms and violence. Instead, it restricts government funding from being used to advocate or promote gun control," the NRA said in a public post on Twitter last year.

Funding for studies on gun violence also may come through other routes, for example from foundations or the National Institute of Justice, but some researchers say that's not enough.

What's left to learn in gun violence data

Such data can "indicate whether each criminal gun possessor was the legal purchaser of the firearm involved in crime, whether the purchaser of the gun that was later used in crime purchased other guns involved in crime, or how crime guns that are diverted for criminal use shortly after a retail sale are distributed across retail gun sellers within an area," he said in the prepared remarks.

The paper involved analyzing data on research funding from 2004 to 2015, and correlating that data with mortality statistics from the CDC from 2004 to 2014.

The paper found that gun violence research had about $22 million or 1.6% of the $1.4 billion in funding that was predicted based on the mortality rate associated with gun violence. Gun violence also made up 4.5% of the volume of research publications that were predicted, the paper showed.

"Gun violence killed about as many individuals as sepsis. However, funding for gun violence research was about 0.7% of that for sepsis and publication volume about 4%," the researchers wrote in that paper. "In relation to mortality rates, gun violence research was the least-researched cause of death and the second-least funded cause of death after falls."

Economist John Lott criticized that 2017 JAMA study in Thursday's hearing and said that one of its problems "is that it ignores all this other funding."

In prepared remarks shared ahead of his testimony, Lott, president of the Crime Prevention Research Center and author of "The War on Guns," said people have been misled "into thinking that gun violence has been understudied." He said public health research can be "poorly done" and "misleading," and can exclude research by economists, criminologists and law professors.

"The money spent is likely to be counterproductive to saving lives. If there are too few resources being devoted to firearms research, it lies in areas outside of Public Health. Any government funded research must strive to obtain quality research that will actually help save lives," Lott's prepared remarks said.

Webster said in his testimony at the hearing that he believes weaknesses in public health research on gun violence "are often due to the modest levels of funding that limit the amount and type of data that are collected and analyzed."

Overall, "I'd want to see renewed interest and many more resources devoted to the scientific study and prevention of gun violence," said Charles Branas, professor and chair of the department of epidemiology at Columbia University's Mailman School of Public Health in New York, who was senior author of a gun violence study published in the medical journal The BMJ on Wednesday.

The study found that states with more permissive gun laws had higher rates of mass shootings compared with states with more restrictive laws. Also, a growing divide in mass shooting rates appears to be emerging between those restrictive and permissive states, according to the study.

"More specifically, the rate of mass shootings in permissive states appears to be increasing since 2010, while the rate in restrictive states appears to be decreasing," said Branas, the study's senior author.

"We were somewhat surprised most by the recent, growing divergence in the rates of mass shootings between permissive and restrictive states," he said.

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The study involved data from the Federal Bureau of Investigation's Uniform Crime Reporting System. That data, from 1998 to 2015, was used to calculate mass shooting rates in each state. A mass shooting was defined as an incident in which four or more people were killed by a firearm.

The researchers also developed an annual scale of how restrictive or permissive gun laws were in each state, based on the 1998-2015 edition of "Traveler's Guide to the Firearms Laws of the Fifty States," a report published by legal professionals for gun owners who travel between states.

Scores on that scale were given to each state depending on how restrictive or permissive their gun laws were based on various factors, such as requirements around permits and standard firearms ownership or whether semi-automatic, high-capacity magazines, machine guns, or suppressors were permitted or restricted in a state.

The study found that a 10-unit increase in a state's gun law permissiveness score was associated with an 11.5% higher rate of mass shootings, and a 10% increase in state gun ownership was associated with a 35.1% higher rate of mass shootings.

The study had some limitations, including that the findings were associations and not evidence of causation.

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"It's hard to be 100% certain that what we found isn't possibly because states that experience more mass shootings in turn changed their gun laws, or some other factors that we just couldn't measure," Branas said.

Additionally, there are concerns about potential under-reporting of data in the Uniform Crime Reporting System, and the study only looked at mass shootings, not shootings involved in other crimes or overall crime rates.

All in all, Branas said, "For mass shootings, we'd love to see more of a call for better data collection on these tragedies and funding for new scientific study of which specific laws are accounting for the differences between permissive and restrictive states that we are just now finding."