America is witnessing a troubling increase in deaths among its children and teens, according to a new mortality report from the Centers for Disease Control and Prevention.

The report, which was released Friday, is based on information from death certificates filed in all 50 states and Washington, D.C.

Between 2013 and 2016, the total death rate for young people ages 10 to 19 years old grew 12 percent, largely due to a significant increase in injury-related deaths, such as drug overdoses, homicides, car crashes and suicides.

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"When I first conceded to do this report 2 ½ years ago, I thought that we would be documenting a decline," report author Sally Curtin, a statistician at the CDC, told CNN. "We were surprised that there was such a broad increase across so many causes of death. There wasn't just one that was contributing."

Before 2013, the total death rate among the same age group had declined 33 percent since 1999. According to the CDC, the substantial decline was due to the marked reduction in deaths for infectious diseases.

Here's what the CDC discovered about what's killing America's teens:

Injury deaths are behind the recent increase.

According to the report, for people age 10-14 years and 15-19 years, the increases in total death rates were attributable to increases in injury deaths, such as suicide, homicide, unintentional injury or legal intervention and war.

The injury death rate among 10- to 14-year-olds increased 11 percent between 2012 (6.4 deaths per 100,000) and 2016 (7.1 per 100,000). Among the older age group, the injury death rate increased 19 percent between 2013 (32.8) and 2016 (39.0).

Noninjury deaths, on the other hand, are not.

Noninjury deaths refer to natural causes of death, such as cancer or heart disease. The noninjury death rate among American children and adolescents was relatively stable through 2016 after a decline in the previous decade.

Car crashes, drownings and poisonings.

According to the report, motor vehicle traffic, drowning and poisoning accounted for 85 percent of all unintentional deaths in 2016.

Motor vehicle traffic fatalities accounted for 62 percent of these unintentional injury deaths. Poisoning accounted for 16 percent, followed by drowning at 7 percent.

“The poisoning deaths do include drug overdoses: Ninety percent of poisoning deaths are drug overdoses, and most of them are in older adolescents,” Curtin told CNN.

Firearms, cutting and piercing and unspecified methods.

Firearms were the leading method of homicide death for Americans ages 10-19 between 1999 and 2016. In 2016, firearms accounted for 87 percent of all homicides and 43 percent of all suicides. The firearm-homicide death rate increased 28 percent between 2014, at 3.2, and 2016, at 4.1.

Homicides involving cutting and piercing were the second leading method of homicide among 10- to 19-year-olds. However, there’s been a decline in related deaths in recent years. The 2016 cutting and piercing homicide rate: 0.3.

Unspecified or missing methods of homicide deaths have declined as well (0.1 in 2016).

Suicide rate up 56 percent between 2007 and 2016.

Suicide rates among those ages 10-19 rose 56 percent between 2007 and 2016, with greater increases for females than males. According to emergency department data, there has also been an increase in visits for nonfatal self-harm, known to be a precursor to suicidal behavior, the CDC reported.

Suffocation, firearms and poisoning accounted for more than 92 percent of all suicide deaths in 2016.

In 1999, the rate of suicide involving firearms was double that of suffocation. But in 2016, suffocation was the leading cause of suicide among children and adolescents.

Related: Study says most Americans feel lonely, young adults are the loneliest

Firearms accounted for 9 in 10 suicide deaths for victims ages 10-19 between 2014 and 2016. Firearms were the leading suicide method for males in that age range, whereas suffocation was the leading method for females.

The number of suicide deaths by poisoning, primarily involving opioid drug overdoses, was higher for females than for males.

Last year, the CDC reported that suicide rates among 15- to 19-year-old girls doubled between 2007 and 2015, reaching a 40-year high.

Still, suicide is still believed to be underreported, particularly when it comes to suicide involving drug overdoses and how medical examiners rule deaths based on evidence.

"Most suicides are preventable with appropriate resources and counseling and by creating more barriers to lethal forms of self-harm, for example by locking up firearms and keeping them unloaded," Dr. Thomas Weiser, a trauma surgeon at Stanford University Medical Center who was not involved with the CDC report, told CNN. "Without a doubt, easy access to guns drives the homicide rate in the United States. This is such a fundamental issue to address through gun safety programs that are effective and widespread."

If you or anyone you know is contemplating suicide, or if you are concerned for someone else, some helpful resources are below.

National Suicide Prevention Lifeline (24 hours): 1-800-273-8255

National Suicide Prevention Lifeline online chat

Suicide prevention resources for parents, guardians and families

Suicide prevention resources for teens

Suicide prevention resources for survivors of suicide loss

More resources are at the Suicide Prevention Resource Center website.