A 4-year-old boy who apparently shot himself in the head early Tuesday morning adds to an increasing tally of children in greater Harris County over the last year who have gotten hold of firearms and injured themselves – sometimes fatally.

Authorities arrived at the Cypress home in the 15400 block of Redbud Berry Way shortly after midnight. They found the child breathing, but unresponsive.

He was transported on Tuesday morning to Memorial Hermann in the Texas Medical Center in critical condition.

The boy, whose name has not been released, was visiting with his grandparents. They were "cooperating with investigators fully," according to the Harris County Sheriff's Office.

Child Protective Services has opened an investigation in addition to a criminal probe by law enforcement. A sheriff's office statement said its findings will be forwarded to a grand jury.

At least four children were killed statewide in accidental firearm discharges with confirmed cases of abuse or neglect last year, according to CPS data, but the number of dead Texas children is much higher when counting shootings in which authorities did not blame adults.

CPS spokeswoman Estella Olguin said the agency has no prior involvement with the family in the most recent incident.

A case worker visited the hospital on Tuesday and was scheduled to see the boy's siblings – a 2-month-old and a 2-year-old. Olguin said she was not sure whether those children reside with the grandparents. The mother, who is in her 20s, was not at the home when the shooting occurred.

An agency official will "interview the grandparents to see how the child gained access to the gun and work closely with police to see what they've learned from their investigation," Olguin said.

In 2015, at least four kids died in Harris County in accidental shootings.

Last July alone, three minors were shot.

A 3-year-old in Spring injured himself with his grandfather's handgun. An 11-year-old boy was shot in the chest during a northwest Harris County carjacking.

By the end of the month, 8-year-old Jadon Johnson was shot to death as he and another boy played with a gun inside a home near Hobby Airport where neither lived.

Adults can be prosecuted for making a firearm accessible to a minor, a misdemeanor, or endangering a child.

So far this year, a toddler has shot himself in the hand and a 15-year-old was killed last weekend by an older brother.

On Jan. 3, a Montgomery County man who had been cleaning his handgun got distracted and laid the weapon within reach of his son, authorities said. That's when the 2-year-old injured himself. The teen died on Jan. 16 in southwest Houston in what police described as an accidental shooting.

According to the Texas Department of State Health Services data, about a dozen minors in Texas die annually because of the accidental discharge of firearms. Ten children ages 0 to 17 statewide perished in 2013, the latest year of complete data available. In 2012, 13 died and 10 were fatally wounded in 2011.

Everytown for Gun Safety, a gun control coalition funded by former New York City Mayor Michael Bloomberg as part of his crusade against firearm violence and to politically challenge the National Rifle Association, tracks media reports about accidental shootings by children. Recently released data compiled by the organization shows that at least 265 children unintentionally shot themselves or someone else in 2015. Seventeen of those incidents were in Texas.

The group found that improper gun storage led to most of the unintended deaths. Two-thirds happened in a home or vehicle belonging to the victim's family and most often with legally owned guns that were not secured.

No one answered the door on Tuesday morning or early afternoon at the one-story brick home where the latest Harris County child shooting happened.

A few doors down, Greg Davis stood in his driveway and lamented the tragedy that had befallen his neighborhood.

"It's heartbreaking," the 35-year-old store manager and father of two young sons said. "I heard it was an accident. It's tragic. My heart goes out to the family and I will certainly be praying for them and praying for the little boy's recovery."