Two people were killed and at least four others wounded in a shooting attack at the University of North Carolina in Charlotte.
Local media reported two people suffered life-threatening injuries, while another two were being treated for less serious wounds.
The local Fox television affiliate identified the dead as boys aged 17 and 18.
A UNC Charlotte campus police officer carries a tactical shield onto campus as students exit. Source: AAP
The suspect was not immediately identified by police, who set up a media staging area near the school.
But police confirmed the shooter was in custody.
NBC Charlotte identified the shooter as a 22-year-old history student at the campus.
Police secure the main entrance to UNC Charlotte. Source: AAP
People gather across from the campus of University of North Carolina at Charlotte. Source: AAP
"Scene secure. One in custody. No reason to believe anyone else involved," the Charlotte-Mecklenburg Police Department tweeted, adding that law enforcement and university staff were sweeping buildings to round up those still sheltering.
"Run, Hide, Fight. Secure yourself immediately," the university said on Twitter.
The school said on its website the campus was in lockdown and that students and staff should "remain in a safe location".
Video footage posted to social media showed students evacuating campus buildings with their hands raised as police officers ran past them toward the scene of the shooting.
According to its website, the University of North Carolina at Charlotte enrolled more than 26,500 students and employed 3000 faculty and staff.
Charlotte Mayor Vi Lyles said she was "in shock" after hearing of the rampage.
"My thoughts are with the families of those who lost their lives, those injured, the entire UNCC community and the courageous first responders who sprang into action to help others," she wrote on Twitter.
The shooting comes just days after a teenage gunman opened fire on a synagogue in Poway, California, killing one person and injuring three others.
