one of the safest large cities in the United States. In 2019, the FBI named Austin the 11th safest city on a list of 22 American cities with a population above 400,000. FBI statistics show that overall violent and property crimes dropped in Austin in 2015, but increased in suburban areas of the city. One such southeastern suburb, Del Valle, reported eight homicides within two months in 2016. According to 2016 APD crime statistics, the 78723 census tract had the most violent crime, with 6 murders, 25 rapes, and 81 robberies. The city had 39 homicides in 2016, the most since 1997. Notable incidents One of the first American mass school shooting incidents took place in Austin on August 1, 1966, when Charles Whitman shot 43 people, killing 13 from the top of the University of Texas tower. The University of Texas tower shooting led to the formation of the SWAT team of the Austin Police Department. In 1991, four teenage girls were murdered in a yogurt shop by an unknown assailant(s). A police officer responded to reports of a fire at the I Can't Believe It's Yogurt! store on Anderson Lane and discovered the girls' bodies in a back room. The murders remain unsolved. In 2010, Andrew Joseph Stack III deliberately crashed his Piper PA-28 Cherokee into Echelon 1, a building in which the Internal Revenue Service, housing 190 employees was a lessee of. The resulting explosion killed 1 and injured 13 IRS employees, completely destroyed the building and cost the IRS a total of $38.6 million. (see 2010 Austin suicide attack) A series of bombings occurred in Austin in March 2018. Over the course of 20 days, five package bombs exploded, killing two people and injuring another five. The suspect, 23-year-old Mark Anthony Conditt of Pflugerville, Texas, blew himself up inside his vehicle after he was pulled over by police on March 21, also injuring a police officer. In 2020, Austin was the victim of a cyberattack by the Russian group Berserk Bear, possibly related to the U.S. federal government data breach earlier that year. On April 18, 2021, a shooting occurred at the Arboretum Oaks Apartments near The Arboretum shopping center, in which a former Travis County Sheriff's Office detective killed his ex-wife, his adoptive daughter, and his daughter's boyfriend. The suspect, who was previously charged with child sexual assault, was arrested in Manor after a 20-hour