School Violence

In this still frame image taken from video provided by the Texas Rangers and recorded on Sept. 8, 2016, armed law enforcement officers move through a hallway at Alpine High School in Alpine, Texas, while responding to a shooting at the school. A Homeland Security Investigations Special Agent was wounded during the response after a gun carried by U.S. Marshal Douglas Mullens, upper-right, accidentally discharged. (Courtesy of Texas Rangers via AP)

Sarah Rogstad, right, hugs Morgan Rogstad, grade 9, after being reunited at the Tipler Middle school reunification center on Tuesday December 3, 2019, in Oshkosh, Wis. Earlier, police responded to an officer invloved shooting at Oshkosh West High School after an armed student confronted a school resource officer. (Wm. Glasheen/The Post-Crescent via AP)

Becky Galvan, center, consoles her daughter, Ashley Galvan, a 15-year-old sophomore, with her father Jose Chavez outside Waukesha South High School in Waukesha on Monday, Dec. 2, 2019. Gunshots were exchanged between a student and a school resource officer inside Waukesha South High School, according to school officials. (Mike De Sisti/Milwaukee Journal-Sentinel via AP)

Professor Alex Wai, Vice President of the Polytechnic University, takes in the vandalized campus as he leads a team of school officials and first aid providers to look for holed up protesters on a roof top of the campus in Hong Kong, Tuesday, Nov. 26, 2019. Hong Kong's embattled leader Carrie Lam refused to offer any concessions to anti-government protesters despite a local election trouncing, saying Tuesday that she will instead accelerate dialogue and identify ways to address societal grievances. (AP Photo/Ng Han Guan)

Bryan Muehlberger shares a hug following the memorial service for his daughter, Gracie Anne Muehlberger, 15, at Real Life Church, Saturday, Nov. 23, 2019, in Valencia, Calif. Muehlberger was one of two students killed Nov. 14, 2019, shooting at Saugus High School. (Dean Musgrove/The Orange County Register via AP)

FILE - This Nov. 14, 2019 file photo shows students being escorted out of Saugus High School after a shooting on the campus in Santa Clarita, Calif. Authorities say the teenager who shot five classmates, killing two, at a Southern California high school used an unregistered "ghost gun." Los Angeles County Sheriff Alex Villanueva Villanueva told media outlets Thursday, Nov. 21, 2019 that Nathaniel Tennosuke Berhow's semi-automatic handgun had been assembled and did not have a serial number. Authorities are still working to determine how Berhow got the handgun. Berhow died from a self-inflicted gunshot wound after the shooting. (AP Photo/Marcio Jose Sanchez, File)

Chicago Police investigate the scene where an officer was shot by a suspected bank robber in the 4300 block of West Irving Park Road, Tuesday night, Nov. 19, 2019. A 15-year-old boy was also wounded in the shooting, while the suspect was shot and killed. (Sam Charles/Chicago Sun-Times via AP)