Police in Knoxville, Tennessee say they are responding to reports of a shooting at a high school, with at least several victims.
One person has been killed in the shooting, Local 10 News reports, citing a police statement.
"Multiple gunshot victims reported, including a KPD officer. The investigation remains active at this time," Knoxville police said on Twitter.
Authorities did not say if the gunman had been taken into custody but the Knoxville News-Sentinel reported that one person had been detained in connection with the shooting.
Television news images showed police and fire crews surrounding Austin-East High School in east Knoxville.
"Knox County Schools is responding to a shooting that occurred this afternoon at Austin-East Magnet High School. We are gathering information about this tragic situation and will provide additional information as soon as possible," Knoxville schools superintendent Bob Thomas said on Twitter.
"The school building has been secured and students who were not involved in the incident have been released to their families," Thomas said.
Local 10 News reported that the school had been placed under a "hard lockdown" and that parents were told to go to the back of the campus to pick up their children.
A string of mass shootings have unfolded across the United States since mid-March.
Last week a man opened fire at the cabinet-making plant in Texas where he worked, killing one person and wounding six others before he was taken into custody.
Eight people were slain at Atlanta-area spas, 10 people at a supermarket in Boulder, Colorado, and four people, including a 9-year-old boy at a real estate office in Orange, California.
Photo Knoxville Police/Twitter