During the brief time that the Senate was in lockdown during an incident which saw shots fired, security used the new Twitter Alert to make sure those inside the building had the most recent and reliable information:
The new system was unveiled by Twitter last week as a more effective way to highlight critical information for users.
More top news
Merrill Lynch has been fined £34.5 million for failing to report 68.5 million transactions, the Financial Conduct Authority has said.
Most people back a change in the law to ban unpaid internships that last for more than four weeks, a new poll suggests.
The favourites to win the Venice marathon finished behind a local runner - after they were led along the wrong route by a motorcycle guide.