One person has been killed and a police officer has been wounded as an armed suspect was confronted at a Tennessee high school.
The shooting, which unfolded on Monday afternoon at Austin-East Magnet School on the east side of Knoxville, was the latest episode of gun violence in the United States since mid-March.
Knoxville police said the injured officer was expected to survive.
"He is conscious and in good spirts," Knoxville Mayor Indya Kincannon told CBS News.
"He's going to be OK. I thanked him for putting his life on the line to protect sutdents and staff at the school. He said he'd rather be hurt than anybody else."
Investigators did not immediately identify the suspect or slain victim except to say they were both male. It was not immediately clear if either attended Austin- East Magnet School.
"Based on the preliminary investigation, Knoxville Police Department officers responded to Austin-East Magnet High School on the report of a male subject who was possibly armed in the school," police said on Facebook.
"Upon approach of the subject, shots were fired. A KPD officer was struck at least one time and transported to the (University of Tennessee) Medical Center with injuries that are not expected to be life-threatening.
"One male was pronounced deceased at the scene, while another was detained for further investigation."
The police department initially reported "multiple gunshot victims" in the attack.
"Knox County Schools is responding to a shooting that occurred this afternoon at Austin-East Magnet High School," Knoxville schools superintendent Bob Thomas said on Twitter.
"We are gathering information about this tragic situation and will provide additional information as soon as possible.
"The school building has been secured and students who were not involved in the incident have been released to their families."
US Bureau of Alcohol Tobacco and Firearms agents were en route to assist other law enforcement agencies, the bureau's Nashville office said on Twitter.
Police established a reunification site for families of the students at the baseball field behind the high school.
One mother who had been separated from her daughter was waiting elsewhere near the school and was relieved to receive a text message from her that she was safe.
In other shootings since mid-March, a man opened fire at the cabinet-making plant in Texas where he worked last week, killing one person and wounding six others before he was arrested.
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.