At least 12 passengers were killed after their bus heading towards Maharashtra fell into the Narmada river in Madhya Pradesh's Dhar district on Monday, a senior government official said.
Madhya Pradesh Home Minister Narottam Mishra said 15 people were rescued.
Twelve people had boarded the bus in Indore, he told reporters in Bhopal.
The bus, belonging to the Maharashtra State Road Transport Corporation (MSRTC), was believed to be carrying 30 to 32 people, another official said.
The bus broke the railing of a bridge on the National Highway No.3 (Agra-Mumbai road), situated close to Dhar and Khargone borders, and then fell into the river, he said.
The bus left from MP's Indore city in the morning and was heading to Jalgaon district in Maharashtra, MSRTC officials said.
Twelve bodies have been retrieved from the bus, MP Home Department's Additional Chief Secretary Dr Rajesh Rajora told PTI.
The National Disaster Response Force (NDRF) has rushed to the spot, he added.
After getting information, Indore Divisional Commissioner (Revenue) Pawan Kumar Sharma instructed the Khargone and Dhar collectors to rush to the spot to launch a rescue operation, officials said.
The river current was strong, Mishra said, adding that the rescue operation was on.
The ill-fated bus was from the Amalner depot in Jalgaon district, MSRTC officials said.
The bus departed from Indore city around 7.30 am and was going to Amalner, they said.
Officials concerned from Jalgaon rushed to the accident spot.
The MSRTC officials said they were in touch with the local administration which was conducting the search and rescue work at the spot.