American Marconi Wireless News - Indian forensic teams scour deadly Delhi car explosion

Police have not given details on the cause of the explosion, which also left at least 19 people injured, when intense flames ripped through other vehicles near the landmark Red Fort in the crowded Old Delhi quarter of the city.

Home Minister Amit Shah told reporters late Monday that the security forces were "keeping all angles open", adding it was "very difficult to say what caused the incident" until forensic samples had been analysed.

At dawn on Tuesday, AFP reporters at the site of the explosion said police white sheets had been erected around the charred remains of vehicles overnight.

Both forensic and anti-terrorism agencies were searching for evidence, while security was increased across New Delhi.

Prime Minister Narendra Modi offered his condolences to the families of those killed, and said he had "reviewed the situation" with Shah.

"Condolences to those who have lost their loved ones in the blast in Delhi... may the injured recover at the earliest," Modi said in a statement.

The 17th century Red Fort is one of India's most well-known landmarks.

Prime ministers address the nation from its ramparts on Independence Day, and it features on the largest banknote.

- 'People were burning' -

Both forensic and anti-terrorism agencies were deployed at the site.

Citing hospital authorities, New Delhi's deputy chief fire officer AK Malik told AFP that "eight people have died so far and 19 are injured".

The Press Trust of India news agency on Tuesday reported that the toll had risen to nine dead.

Eyewitnesses described to AFP how the car exploded in traffic and how people caught up in the surge of flames were set on fire.

"I saw the car explode while it was moving," said Dharmindra Dhaga, 27.

"People were on fire and we tried to save them... Cars and people were burning -- people inside the cars were burning," he added.

"I was telling the public to save them, rescue them, and get them out. The public was busy making videos and taking photos."

After the explosion, at the city's LNJP hospital, the emergency ward was chaotic as injured people streamed in and doctors rushed to attend to them.

A woman broke down outside the ward where her husband was being treated.

"I can't bear to see him like that," she said, as her brother tried to console her.

Opposition leader Rahul Gandhi said in a statement that the deaths from the explosion were "heartbreaking".

The US State Department said its "hearts are with those affected by the terrible explosion", and that it would "continue to closely monitor the situation".

D.Sawyer--AMWN