On Friday morning, I was nearing the end of an hour-long meeting with our HR team, when one of my team knocked on the window, calmly waited for me to pop my head round the door and said we all needed to leave the building immediately because there was a man next door threatening to blow himself up. In actual fact, I think they might have said the man was threatening to shoot people, because I distinctly remember milling around outside a few minutes later pondering whether we wouldn't, in fact, be safer inside the building.
At this stage, there weren't any police, zero helicopters circling overhead and certainly no news cameras, just our head of facilities telling us it looked like it might be an hour or more before we could get back into the office and it was probably okay to head off and get an early lunch.
Except of course, we're an office that houses quite a few journalists. Food wasn't the priority, finding out what was happening was. I finally ate about eight hours later, slumped on the sofa at home, trying to make sense of how the afternoon unfolded.
We know now that a man believed to be Michael Green, a 48-year-old former member of the Royal Electrical and Mechanical Engineers from Stevenage, had marched into the offices of the training company Advantage HGV, adjacent to HuffPost HQ, disgruntled about failing his HGV training course and, according to those inside at the time, threatening to blow up both himself and the building.
Thanks to smartphones, Twitter and a team with a good, old-fashioned nose for news reporting, not only did we manage to track and follow the story, we quickly became the source of information spreading out across the web, radio and TV stations. The only unforeseen stem in the tide of updates coming as one by one iPhones and Blackberries ran out of battery - technology may have advanced, but it appears unprepared for more than a few hours of simultaneous calls, Tweets, texts and typing. Thankfully, our News Editor, Jacqueline Head, proved that her charms of persuasion when it comes to pub landlords and their phone chargers are as well-honed as her abilities to edit a great story.
At a time when social media is getting a bad rap for spreading mis-information, Twitter - or more correctly the journalists using Twitter - proved that when combined with traditional methods of reporting, it can also be one of the best way of updating and correcting as you go, instantly adding to the story as more information becomes available.
If this incident showcased social media sites as news outlets at their very best, it also showcased London at its best. While the naysayers still furrow their brows with concern over how the city will deal with the tidal-swell of people arriving for the Olympics this summer and the inevitable terrorist alerts, Friday's alarm proved issues can be dealt with calmly and ultimately successfully. The police were quick on the scene, the general public did as they were told (even the nosy reporters amongst them) and everyone pitched in to help. From door-men at the nearby Spearmint Rhino, who helped move the crowds back as the police cordon widened, to owners of local hotels and restaurants who took people in and then locked down their doors, feeding and watering the crowds.
This may have been a false alarm of sorts, albeit one that left those it affected directly shaken and traumatised, but the capital jumped into action and dealt with everything as calmly as you can when there are snipers on the roofs and armed police-officers patrolling the streets.
Within hours it was as if nothing had happened and everything went back to normal. We, in the meantime, are implementing a don't-leave-the-office-without-your-phone-charger policy.