A lone gunman killed four—including an NYPD officer—inside a Manhattan skyscraper before taking his own life, exposing vulnerabilities in corporate security and reigniting debate over lone-actor violence.

Authorities arrested 21-year-old Seth “Andrea” Gregori in Corpus Christi, Texas, for allegedly planning an attack on police officers similar to the 2016 Dallas ambush. The FBI and CCPD launched an investigation after receiving reports of terroristic threats, leading to Gregori’s arrest. The investigation remains ongoing, with prosecutors awaiting further details before filing formal charges.

A mass shooting at Campus Risbergska in Orebro, Sweden, has left around 10 dead, including the suspected gunman, as authorities investigate the motive behind one of the country’s deadliest school attacks.