Two students -- both also aged 15 -- died of gunshot wounds, while 12 other people were shot and five suffered other injuries during the shooting, Kentucky Governor Matt Bevin told a news conference.

One of the students died at the scene and the other after being airlifted to a hospital, he said.

The young male suspect was apprehended in a "non-violent" manner, and will be charged with both murder and attempted murder, said Bevin.

Kentucky State Police Commissioner Rick Sanders said the shooter struck just as the school day was starting.

"The incident began at 7:57 am (1357 GMT) when a 15-year-old student armed with a handgun entered the high school and started shooting," Sanders told journalists.

A 911 emergency call was placed soon after, and first responders were at the scene by 8:06 am, he said.

State police had recently been in the area "teaching students and faculty how to respond to an active shooter situation, and everybody in that high school reacted appropriately," he added.

US plagued by mass shootings

Sanders said that an "SRO," or "School Resource Officer" -- a law enforcement officer responsible for safety at the school -- was present, but did not provide further information on the officer’s actions during the shooting.

Students ran from the scene after hearing shots, the Marshall County Tribune-Courier newspaper reported on its Facebook page, adding that the school was placed on lockdown as the incident unfolded.

Students later were bused to a neighboring school where parents could retrieve them, it said.

"This is a tremendous tragedy and speaks to the heartbreak present in our communities," Bevin said a statement. "It is unbelievable that this would happen in a small, close-knit community like Marshall County."

According to Everytown for Gun Safety, an NGO that works to reduce gun violence, the most recent school shooting in Kentucky occurred in September 2014, when one student shot and wounded another in the hallway of Fern Creek High School in Louisville.

The US as a whole is plagued by mass shootings, including two in recent months that left dozens of people dead.

In October, a shooter opened fire on a country music concert from a Las Vegas hotel, killing 58 people, while another attacked a Texas church the following month, leaving 26 people dead, including an unborn child.

Guns are the source of one of the most bitter and enduring divides in American politics.

Most Democrats advocate gun control as a means of reducing deadly shootings, while many Republicans -- backed by the powerful National Rifle Association gun lobby -- oppose restrictions on firearms ownership, arguing that armed citizens are better able to protect themselves from gun violence. — AFP