As I soon came to realize, the 11 a.m. scheduled start for Benazir Bhutto's campaign rally in Rawalpindi, Pakistan, was a little over-ambitious. It wasn't until mid-afternoon before the park where the rally was to be held was full enough for her arrival. At the time I was surprised to see her standing up with her head and shoulders out of the sunroof of her vehicle as the convoy crawled through the thronging crowd with no barriers between her vehicle and her enthusiastic supporters, but thought little of it.

In the climate of fear surrounding Bhutto and Pakistan in general, due to the deteriorating security situation and massive double suicide bombings that marred her homecoming in October, the days of hundreds of thousands of supporters attending political rallies were a thing of the past. On my way to the rally both my hotel concierge and taxi driver had warned me of the dangers of attending Bhutto's rally as there had been another suicide bomber apprehended before detonating his explosives at a rally the previous day in Peshawar. With the benefit of hindsight, it seemed like the writing was on the wall.

The security at the gates into the park was very thorough and once inside the security seemed much better organized and the rally went ahead as expected. There were a handful of local wire photographers there along with John Moore of Getty Images and myself. We were leaving after the rally, assuming Bhutto would make a quick exit for security reasons, but hundreds of supporters managed to break through the barriers in the park and surround her convoy as she tried to make her departure. Once again she came out of the sunroof and started greeting her cheering fans as her vehicle crawled along the road. I was about 20 meters from her vehicle and started shooting with a long lens as it turned and came towards me.

The next course of events is still a bit vague in my mind but basically I heard some gunshots and assumed it was her security firing into the air, trying to clear the crowd so she could get away. It was followed seconds later by a flash and explosion. I realized it was a suicide bomber and immediately feared the worst. I remember being surprised by how small the flash, and quiet the bang, was. It's a cliché but the seconds after the explosion seemed to pass in slow motion and silence. Then as her vehicle sped away, I was knocked back by the crowd that was trying to escape the explosion, thus revealing the carnage right in front of me.

My first thought was disbelief and fear of a follow-up blast but that soon faded when people started crying out and screaming. The dispersing crowd and thinning smoke revealed the hideous aftermath of the bomb. As I approached and started to shoot I struggled to compose myself, concentrate and make sure all the settings on my camera were correct because the light was fading fast. Terrified and sickened by what I was seeing, I kept telling myself to just do my work so I could get out of there.

I started to make some pictures but it was really hard to find images that weren't too graphic for editors to publish because the 'epicenter' of the explosion really was a pile of maybe a dozen limbless, charred, mangled bodies in pools of blood. After what seemed about 5 minutes of survivors stumbling around in dazed confusion, the emergency services arrived, breaking the eerie silence. Most people were in shock but one or two people were very emotional and some even started beating the police vehicle with injured policemen inside that had been damaged in the blast. This was presumably because they held the police responsible for failing to protect Bhutto.

The sense of urgency and panic escalated as people began desperately searching for their missing friends. The rescue workers and police began the gruesome task of loading the many injured and wounded into ambulances and police vehicles ferrying them to the nearby hospital. The light was almost gone and I thought I had what I needed from the scene so I convinced a guy on a motorbike to take me to the hospital where a large crowd had gathered at the gate. The police were only letting ambulances in so we waited for the next ambulance and followed that in but the hospital entrance doors were heavily guarded. I went around the back and managed to get into the hospital through another entrance.

The reality of what I had witnessed really hit me only when I was inside the hospital, away from the bomb scene. Here the wounded were being carried in as the overwhelmed staff tried to prioritize those who needed urgent attention, those who could wait and those who were beyond help, who ended up being piled on the floor in the corner.

At this stage I thought Bhutto had survived the bomb attack because her vehicle had driven away; I didn't realize that she had been shot. I was the only journalist inside the hospital at the time and soon realized Bhutto was there and seriously injured when I saw her personal security detail, heavily armed with Kalashnikovs, guarding the staircase and elevator to where I assumed she was being treated.

As the news that Bhutto had been assassinated was spreading, people were already taking to the streets and burning vehicles and blocking roads in Rawalpindi and the nearby city of Islamabad where I was staying. I had to try and get my pictures filed as soon as possible and once again had to rely on a friendly motorbike rider to get me through all the roadblocks and traffic.