Police said they were examining “very concerning online writings and social media posts” linked to a teenage gunman who killed a fellow pupil in a Nashville high school cafeteria.
The 17-year-old, named by Metro Nashville Police as Solomon Henderson, killed the female pupil and injured another at Antioch High School before fatally shooting himself.
Police chief John Drake said the gunman “confronted” Josselin Corea Escalante, 16, in the cafeteria and opened fire, killing her.
The wounded pupil, who was grazed by a bullet, was treated and released from the hospital, Mr Drake said.
A school bus arrives at a unification site following the shooting at Antioch High School (George Walker IV/AP)
Metro Nashville Police, federal and state agencies are examining “very concerning online writings and social media posts connected to 17-year-old Solomon Henderson” as they work to establish a motive, police said in a statement on Wednesday evening.
Investigators at this point have not established a connection between Henderson, who was a pupil at the school, and the victims. Police said the gunfire may have been random, according to the statement.
The school has about 2,000 pupil and is in Antioch, a neighbourhood about 10 miles southeast of downtown Nashville.
United Family Fellowship, a church in Antioch, was hosting a vigil on Wednesday night “for anyone in the community who needs a space to pray, process, and find comfort”, the church said on Facebook.
Adrienne Battle, superintendent of Nashville schools, said public schools have implemented a “range of safety measures”, including partnerships with police for school resource officers, security cameras with weapon-detection software, shatter-resistant film for glass, and security vestibules that are a barrier between outside visitors and the main entrance.
“Unfortunately, these measures were not enough to stop this tragedy,” she said.
She said there are questions about whether stationary metal detectors should be considered.
“While past research has shown they have had limitations and unintended consequences, we will continue to explore emerging technologies and strategies to strengthen school safety,” she said.
In October, a 16-year-old Antioch High School student was arrested after school resource officers and school officials discovered through social media that he had taken a gun to school the day before.
When he was stopped the following morning, officials found a loaded gun in his pants, police said.