The blast occurred in a car near the Red Fort, but the exact cause was not immediately known, and was being investigated, city police spokesperson Sanjay Tyagi said.
Visuals on local media showed flames and smoke billowing from more than one vehicle in what was described as a congested street located near a metro station in the old part of Delhi.
At least six vehicles and three autorickshaws caught fire, Delhi’s deputy fire chief said, adding that the flames had been doused by firefighting teams.
“We heard a big sound, our windows shook,” one resident who did not give a name, told NDTV.
Police tried to clear crowds that gathered around the site of the incident.
The Red Fort, known in India as the Lal Qila, is a 17th-century, Mughal-era fort located in the old city and visited by tourists through the year.