A tragic series of shooting accidents involving children around Houston has prompted law enforcement officials to implore firearm owners and parents to limit their access. In the past four days, two young children have died and another was wounded in three separate gun incidents in the area.

On Monday, a 5-year-old boy shot his 6-year-old brother in the stomach. Authorities reported that the children were playing with an unsecured gun in a bedroom while the mother was home. Relatives said the boys loved to play cops and robbers, but noted that the real weapons were usually locked away.

"He may have picked up the wrong weapon thinking that it was a toy," said an uncle of the children. "But this weapon was not a toy and it was a real gun and he actually pointed it at my other nephew and fired it."

The injured boy remains in critical condition.

On Sunday morning, 4-year-old Codrick McCall Jr. accidentally shot and killed himself after finding a loaded gun under a bed at the home of a temporary guardian in a northern Houston suburb. He was staying with the caregiver while his parents were under investigation by Child Protective Services.

"My son was being cared for by a temporary guardian," his father said. "I had just dropped him off at that woman's house the night before he died."

That shooting came just two days after another Houston boy found a gun in a purse and fatally shot himself in the neck while his mother was in another room. He was just 3 years old.

Investigations into both of the fatal shootings are ongoing, police said. Though Texas is known for being gun-friendly, firearm owners can be held criminally liable if a minor obtains a gun that was stored negligently.

Harris County Sheriff Adrian Garcia held a press conference on Monday to promote gun safety and stress the use of gun locks. A common type of lock is a metal cable that blocks the gun's chamber and prevents it from discharging a round, and Garcia noted that they can be obtained for free from the sheriff's department.

"I beg of you, help us to keep from having to respond to tragedy that can be prevented," he said. "Help us by asking each and every person who may have a firearm at home — whether you have a young child in your home or not — to practice all of the common sense safety measures that you've heard about."

Of course, Texas isn't the only place in the US that has seen such shootings. Late last year, a 2-year-old pulled a gun from his mother's purse and killed her in an Idaho Walmart.

A spate of incidents within a week this past January gives an idea of how appallingly routine such incidents can be. A 5-year-old shot his 9-month-old brother dead in Missouri; a 3-year-old died in an apparent accidental shooting in Michigan; and a 2-year-old shot and killed himself in Florida.

At least 100 children were killed in unintentional shootings across the United States between December 2012 and December 2013, according to a report on unintentional child gun deaths titled "Innocents Lost." It was co-authored by gun violence prevention organizations Everytown for Gun Safety and Moms Demand Action for Gun Sense in America (MDAGSA), which was founded following the killing in 2012 of 26 children and adults at Sandy Hook Elementary in Newtown, Connecticut.

The report, released last June, points out that the number of unintentional deaths is a fraction of the overall number of child gun-related deaths during that time. It also revealed that of the more than 2 million children currently living in homes with unsecured guns, 1.7 million of them live where guns are unlocked and loaded.

"When a child dies or is injured because a gun is left unsecured in the home, it is not a blameless accident," Stephanie Lundy, a spokeswoman for MDAGSA, said at Monday's press conference. "We owe it to our children to be smarter when it comes to responsible gun ownership."

Other studies have echoed similarly disturbing findings on preventable gun deaths. A survey published last year found that some 28,000 children and teenagers died from guns between 2002 and 2012. A study published last year in the journal Pediatrics determined that firearms are the second-highest cause of death for American children, with 453 deaths and more than 7,000 hospitalizations in 2009, the last year for which there is comprehensive federal data.

The Brady Center to Prevent Gun Violence analyzed data from the Centers for Disease Control and issued a report last month that amplifies the findings of the Pediatrics study.

"Millions of Americans have a gun in their homes thinking that it makes their family safer, but every day in our nation, dozens of these families learn just how dangerous and tragic that miscalculation can be," Dan Gross, president of the Brady Center, said in a statement at the time the report was released. "The bottom line is, having a gun in the home dramatically increases the danger that a child will be shot and killed."

Adults in Texas can be held liable for criminal negligence if authorities find they failed to adequately secure a "readily dischargeable firearm," or left it in a place where a child could find it. Authorities cannot arrest relatives of a child who is shot within 7 days of the incident.