The woman and child died despite the efforts of firefighters to get them out of the blazing wreckage following the crash on the A1 at one of the main entrances to the city.

The accident involved two cars – a Ford Focus and a Toyota Corolla – and is believed to have happened at about 1.15pm yesterday afternoon on the northbound carriageway of the road at Junction 17, near Haddon.

Police said today that the two people killed in the collision were travelling in the Ford and were certified dead at the scene. They had still not been named today.

Meanwhile, the driver of the Toyota, a 59-year-old woman from London, was taken to Peterborough District Hospital with minor injuries.

Firefighters from Stanground and a rescue vehicle from Dogsthorpe were called to the scene and arrived to find the car well ablaze.

The stretch of the A1, close to the junction of the Fletton Parkway, was closed in both directions as police investigations were carried out.

Traffic was diverted onto the roundabout, which connects the A605 with the A1, and there were long traffic queues and delays for more than six hours.

Today, sergeant Tim Elliott, who is heading the investigation into the accident, urged witnesses to come forward.

He said: "I would like to hear from anyone who was travelling on that stretch of the A1 who witnessed the incident or saw either vehicle in the moments leading up to the collision."

Another tragedy came on a stretch of road outside Thorney, near Peterborough on Saturday.

Motorcyclist Richard Teasdale (39), from Thorney, died after the motorbike he was riding – a blue Yamaha Fazer – left Wisbech Road and ended up in a ditch at about 7.55pm.

Sergeant Lyndon Pickston urged witnesses who may have seen the motorbike in the moments leading up to the crash to come forward.

Anyone with information on either incident should call the Roads Policing Unit on 0845 456 4564.