LAS VEGAS -- The gunman who killed four people before taking his own life in a midtown Manhattan office building that houses the NFL's headquarters had for years sought medical help for frequent, ...

(CNN) — During evening rush hour in New York City on Monday, a man calmly walked into a Park Avenue office building lobby and killed a police officer, then opened fire on other innocent strangers.

Officer Didarul Islam, 36, who was guarding the building on a paid security job when he was killed, had served as a police ...

What we know about Tamura’s life, how he got the assault rifle that he used to kill an NYPD officer and three others, and the ...

After a deadly shooting at an NYC building that housed NFL and Blackstone offices, safety experts say it’s high time ...

A man stalked through a Manhattan office tower firing a rifle, killing four people, including a New York City police officer, ...

Most of the damage was relegated to the 33rd flood, where Shane Tamura accidentally rode the elevator while searching for the ...

Authorities confiscated several items from a Las Vegas apartment tied to a gunman who used an AR-15-style rifle to kill four ...

A Blackstone executive was seemingly a random victim in a mass shooting that left four dead, but some see parallels with the ...

A security expert offers a list of ‘must-haves’ for workplace safety that may save lives in the event of a mass shooting.

There were 23 shell casings and 13 bullet fragments recovered from the lobby of 345 Park Avenue and 24 spent shell casings on ...

Craig Clementi, who works in the NFL's finance department, took a bullet in the back during the tragic mass shooting on ...