NEW DELHI: At least 21 revellers were killed en route to a wedding when their truck flew off a bridge, police said Wednesday, the latest horrific crash on India's accident-prone roads, reports AFP.

The truck, carrying more than 40 passengers, smashed through a protective railing in central Madhya Pradesh state late Tuesday and plunged nearly 20 metres to a dry riverbed below.

Police in Sidhi district said 21 people were injured, most of them critically, in the accident some 560 kilometres (350 miles) from the state capital Bhopal.

"Several teams of police and emergency services were rushed to rescue the injured. Most of the injured were in a critical condition," local police officer Vishal Sharma told AFP.

The immediate cause of the accident was unknown but Sharma said the driver was likely speeding.