(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 ...

It's a point borne out by recent research from ASIS International, a global organization of security professionals, that showed 14% of companies had no comprehensive plan to address active-assailant ...

A flatbed truck carried a digital billboard showing photos of Officer Didarul Islam and a commemorative message from his union.

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

Police have identified the man who entered a Midtown Manhattan office building wearing body armor and opened fire killing ...

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

Roger Goodell also gave a health update on the league employee who was seriously injured in the gun attack that killed four ...

Four people, including an off-duty New York City police officer, were killed Monday when a gunman carrying a rifle opened ...

New York City is mourning NYPD Officer Didarul Islam and three other people killed in Monday's shooting inside an office ...

In New York City and elsewhere, financial institutions are taking stock of their office-building security protocols following ...