Authorities in Washington state have announced that five people were killed in a mass shooting at a residence near Seattle, and a 15-year-old is in custody.

The King County Sheriff's Department confirmed that three children and two adults were fatally shot and a little girl who lived in the house also sustained injuries. 

The Sheriff's Department spokesperson Mike Mellis told reporters on the scene that deputies apprehended the offender, citing it was unclear whether all individuals involved were of the same family. 

It said it was still investigating the motivation for the fatal attack.

According to the department, deputies responded to several reports of a shooting at a residence in Fall City, approximately 10 miles east of Seattle, early Monday. A neighbor "with some medical training was able to administer first aid before first responders arrived," according to the department. 

The arrested teen was put into the King County juvenile detention center and is scheduled to appear in court for the first time on Tuesday.

The incident is the latest in a string of deadly gun attacks across the US in recent years.

Only last week, a man was killed and nine other people were injured in a mass shooting near Tennessee State University as the Nashville school celebrated homecoming. Investigators believe at least one of the injured participated in the gunfire, officials said.

At least three of the injured were juveniles who had non-critical injuries, Nashville police said on X.

US gun violence: Debate intensifies as firearm deaths soar

Gun violence is a frequent issue in the United States, where there are more firearms than people. Despite public opinion polls showing a desire for stricter gun regulations, the strong influence of the gun rights lobby, constitutional protections, and a deeply ingrained gun culture create significant political obstacles to enacting tighter controls.

The 2022 gun safety legislation passed by Congress was the most significant in decades, enhancing background checks and supporting states with "Red Flag" laws that allow the confiscation of weapons from individuals deemed high-risk. Nevertheless, advocates argue that more comprehensive measures are necessary.

In that same year, over 48,000 people died from gun-related incidents, prompting the surgeon general to issue a landmark advisory declaring gun violence a "public health crisis."

Gun rights and gun violence are key issues in elections. Republican candidate Donald Trump, viewed as a strong supporter of gun rights, expressed on social media that "our hearts are with the victims" of the Georgia shooting.

On the other hand, Democratic nominee Kamala Harris, a former prosecutor, attorney general of California, and US senator, urged Congress to "finally" pass an assault weapons ban. This proposed ban would mirror the one that President Joe Biden helped draft and pass into law in 1994, which expired after a decade without renewal by Congress.