Her voice sounded distressed over the phone. She is a former journalist and knew what she'd just heard on TV didn't make sense, a sudden power outage on London's Underground.
By the time I was dressed and ran the few hundred yards to our newsroom we knew it was a bomb, probably more than one.
I was in Kabul on September 11, 2001. I hate being away from my family when the world is being roiled by radical fanatics.
Now the attack was in London. My daughters were at school there.
Since long before 9/11, I'd been on the terrorism beat. I've tried to get inside the mindset of the people who plan and carry out these attacks. I know what they are like and what they are capable of.
September 11 was bad, and for a long time I'd feared the United Kingdom would suffer the same.
My mind was racing. What could this be? Who to call?
My worst fear: It could be a so-called dirty bomb. Explosives dispersing low level radiation or even some kind of complex chemical attack. Fanatics released poisonous Sarin gas on the Tokyo subway killing 12 people in 1992.
Keeping my children safe
I wanted to know what we were up against. I called an old friend who'd given me WMD training. I knew with his expertise, he'd know if this was something even more sinister than deadly explosives.
My wife was on the phone again. The school wanted to send the kids home: Put them on buses, let them out on the streets. I told her no, keep them at school until we know more, they are safer there.
We'd seen from the 9/11 attacks that there was no knowing what could come next.
My friend got back to me quickly. As far as he could tell there was no nuclear or chemical component. Through the day we gathered more information. From Atlanta I did my best to support my colleagues in the thick of it in London.
I jumped on a plane as soon as I could, and by late the following afternoon I was in London.
I wanted to go straight home and hug my wife and daughters, but I went to the office and got to work.
For a month it felt we worked around the clock. Following leads, chasing details, retracing the route the bombers took, talking to friends and family. Who were they, why had they done this, and of course how could they get away with it.
Over the following years I'd trace some of their footsteps back to Pakistan, visiting a grave for one of the bombers there too, but nothing surprised me so much as the community most of the four killers came from.
Within days of the attack we were in Beeston, a neglected, once-neat suburb of Leeds -- row upon row of terraced red brick houses in the north of England. Most of the bombers had lived and hung around there.
On the street outside one bomber's house, former friends told us just months before one of the bombers had been a regular of their knockabout soccer games. He'd been good at cricket, said another. They all said they hadn't seen his radicalization coming.
Knocking on doors in that neighborhood was an education: families of Pakistani heritage, trying their best to turn out smart, well-educated kids side-by-side with poor white areas.
By midday some of them were often drunk and belligerent -- a tough neighborhood for sure.
The bomb factory wasn't far away. It was a rented apartment in a nondescript run-down red brick house. Apparently a bath tub had been used to mix up chemicals before tipping it in to plastic pots, one for each bomb. We bought a pot at the time to show how homemade their device was.
We learned more about how they had taken themselves apart from the local community, stopped attending the mosque of their fathers and friends, took up lessons in a small local Muslim study center; about a ring leader, and his trip to Pakistan to learn how to make bombs.
Second bombing attempt
Since then, time and time again, whether in the UK, France, Saudi Arabia, Pakistan or the many other places I've chased terrorism to its roots, we've seen the same basic radicalizing profile. Only today it's supercharged, fueled by ultra-radicals like ISIS, funneling their gutter-garbage craziness to gullible youths through the Internet.
But in those weeks after 7/7 even those of us familiar with terrorism were still on a steep learning curve.
Two weeks later came the next shock, four more young men trying to mimic the 7/7 attack. They too strapped explosive-laden backpacks to their torsos and took to public transport.
Startled bus travelers watched in horror as frothing yellow paste oozed from their bags. Realizing they'd screwed up, the men all ran off.
They were from East Africa and were caught unceremoniously several days later -- one emerging semi-naked on a second floor balcony as police marksmen trained their weapons on him.
The country felt it was on a knife edge. We just didn't know what was coming next.
One morning after yet another late night's reporting, before I could even get to the office I was diverted to Stockwell Tube station. A young man had been shot dead by counterterrorism police who thought he might have been another bomber.
It turns out the man, Jean-Charles de Menezes, wasn't a threat.
It might have been painful to watch at the time, but the security services were getting a grip.
Soon the 7/21 bombers' factory was found, right under the noses of their neighbors, the trash cans outside full of the detritus a modern warfare lab leaves in its wake. How they had gone undetected shocked me.
The way they bought the raw ingredients was something the government quickly shut down.
Jihadis as neighbors?
In 10 years, we've become a country of vigilance. But how to tell who is who?
A good acquaintance I've known for many years, who lives not far from me, woke to find camera crews outside her house earlier this year. A man who lived in a home near hers is widely reported to be Jihadi John, the infamous ISIS executioner.
She told me there are plenty of youths who make trouble in her area. She worries about her daughters and has all but given up getting help to stop neighborhood crime. But never in her wildest dreams did she think the kid she used to pass on the pavement would grow up to cut people's heads off.
Now 7/7 seems like a long time ago, but I still have that plastic pot we brought to show the home-made nature of the bombs.
It sits in my office stuffed full of business cards, many of them collected in the pursuit of terrorists.
It is a growing reminder, as if I needed one, of that terrible day.