At least eight people have been killed and more injured after a car exploded near Delhi’s historic Red Fort, authorities have said.

Delhi City police spokesperson, Sanjay Tyagi confirmed the deaths to the BBC, and said a further 20 people had suffered injuries.

Police are investigating the cause of the explosion and “exploring all possibilities”, Mr Tyagi said.

Delhi Police Commissioner Satish Golcha has told reporters that the incident happened at around 18:52 local time (13:52 GMT), when a slow-moving vehicle stopped at a red light before it exploded, damaging nearby vehicles.

Mr Tyagi told the BBC the explosion happened in a Hyundai i20 car that was moving and carrying three people at the time.

Mumbai, India’s financial capital, has been put on high alert, as has the Uttar Pradesh state which borders Delhi.

The blast happened near a metro station close to the Red Fort, one of Delhi’s most high-profile landmarks.

The Mughal fortress, which is visited by thousands of tourists each year, was built in the 17th Century and is where Indian prime ministers give their Independence Day speeches every year.

India’s Prime Minister Narendra Modi has sent his condolences to those who lost loved ones in the blast.

Opposition leader Rahul Gandhi said in a statement that the news was “extremely heartbreaking”.

The federal home minister Amit Shah said teams from India’s National Security Guard, and National Investigation Agency are investigating the explosion, along with forensic experts.

“We are exploring all possibilities and will conduct a thorough investigation, taking all possibilities into account. All options will be investigated immediately and we will present the results to the public,” he added.

The minister, who visited the site of the explosion and a nearby hospital, said a meeting involving senior officials would be held on Tuesday morning.

Security is being stepped up at “sensitive religious sites, vulnerable districts and border areas” in the northern state of Uttar Pradesh, according to senior police official Amitabh Yash following the blast in neighbouring Delhi.

Uttar Pradesh is home to famous sites such as the Taj Mahal and is a densely populated state.

Veeru Sindhi, a local businessman at the site when the explosion happened, described scenes of devastation, with multiple bodies and vehicles engulfed in flames.

“I am fully shaken by what I have seen,” he told the BBC. “We tried to rescue people who were trapped inside the vehicles.”

One eyewitness described the aftermath of the blast as chaotic and confusing.

He was just a few hundred metres away from the spot when he heard a loud explosion.

“It felt like everything stopped for a few seconds before everyone started running in all directions,” he told the BBC.

He did not go near the site but could see mangled car parts on fire and locals trying to help the injured.

There has been a heavy security presence at the blast site with personnel from the Uttar Pradesh Anti-Terrorist Squad (ATS), the National Security Guard (NSG), and the Central Reserve Police Force (CRPF). Armed officers have been seen moving towards the area as investigations continue.

Additional reporting by Charlotte Scarr and Dilnawaz Pasha.