But this was not a normal Saturday afternoon. Unnoticed by traders or shoppers, someone had slipped a blue holdall between the market stalls. Despite the hundreds of alarms over the years and the dozens of bombs - the capital city, after all, has had its fair share of explosions - it was eventually spotted by people whose first reaction was merely to wonder what it contained and who might have left it there.
At 5.25pm they found out. Someone bent on destruction. Inside the holdall was a lethal explosive device packed with nails. Passers-by, including young children, were hit by the nails. One became embedded in a baby's cheek; another in a boy's foot. A man was hit in the chest, with the nail entering a lung. People were flung to the floor, some badly injured, others in shock. Buildings shook, windows were blown out by the blast, and glass lay scattered among the wounded. In the first few seconds after the explosion, there was silence. Then came another huge bang. People started to panic, thinking another explosion had occurred. This time it was thunder. As people began running to and fro in fear, sleet began pouring down.
Amy Mangion had come into Brixton to go shopping. The 32- year-old Channel 5 worker had crossed the road two minutes before the blast and was waiting at a cashpoint machine 200 yards from the Tube station. She heard an explosion and ducked.
"People came running towards me. Then there was just loads of smoke which looked like it was coming from the Tube station. Everybody was panicking and kids were crying. My boyfriend ran down to see what was happening. All he saw was one guy lying on the street. He couldn't see what his injuries were, but he was moving. He was next to a car which had had its windows blown out. Another guy was sitting up and was being nursed."
Jools Thomas was walking back to his flat when he heard the explosion. "It was quite horrifying. There was a flash and then this sonic boom which vibrated everything and then the smoke started billowing out from near the market."
On Brixton Road, Metin Saglam, 34, was busy running her fast-food shop when she heard two bangs. Then came the sound of people screaming "Bomb, bomb, bomb".
"There was a man lying on the floor. I saw this body and a police officer told me there could be two or three more devices, so I left."
Andrew Scott-Bolton, 35, lives 25 yards from the site of the explosion on Electric Avenue. All his windows were blown out. His brother was in Atlantic Avenue, the next road down in his car. "He felt the air suck out and saw a shower of sparks and flame."
Within minutes, the emergency services arrived. Police cordoned off the area, traffic was stopped and passengers were herded off buses. Shops were cleared, and residents of nearby flats were evacuated. There were fears of another device and the police aimed to get people as quickly as possible. Sniffer-dogs and bomb experts searched the area.
Dozens of people, some walking wounded, others very severely injured, began arriving at nearby hospitals, including King's College, and St Thomas's, which had put their major incident plans into action. As staff tended the injured and explained the treatments, there was one question that nobody could answer: who would want to bomb Electric Avenue?