"The mishap occurred around noon at Kanaganamaradi village near Pandavapura town, as the bus skidded off the bridge and fell into the Cauvery river canal," a Mandya police control room official told IANS on phone.

Divers of the district fire brigade retrieved bodies of 30 passengers -- 15 women, 7 men and 8 minors -- from the 40-seater bus before it was lifted by a crane out of the Visveswaraya canal.

The accident spot is about 120 km from Bengaluru on the state highway towards Mysuru after Mandya town.

According to a witness, the speeding bus was on way to Mandya from Pandavapura when the driver apparently lost control of the wheel, resulting in the bus veering off the bridge and falling into the 20-feet deep canal, which does not have a retaining wall.

Vehicular traffic on the state highway was disrupted and rescue work affected, as hundreds of people from the surrounding areas thronged the mishap spot to see the bus plunged into the canal.

Another witness said about 10 passengers of the bus, however, survived the mishap by emerging out of the plunged bus and swam to the canal bank.

A few students were among the victims as they were returning home from schools and colleges which had half-day classes as it was Saturday.

Chief Minister H.D. Kumaraswamy, who visited the mishap spot to condole the deaths, announced an ex-gratia of Rs 5 lakh each to the kin of the 30 victims.

"An ex-gratia of Rs 5 lakh would be paid to the families of the victims who lost their lives in the tragic accident," a statement from the Chief Minister's Office said.

"This is a tragic incident. I pray for peace to the souls of the deceased and strength to their families to bear the loss," Kumaraswamy said in the statement.

Former Chief Minister Siddaramaiah, state Transport Minister D.C. Thammanna and district in-charge Minister C.S. Puttarajau also visited the accident spot with district Deputy Commissioner N. Manjushri and Superintendent of Police S.P. Devaraj to console the bereaved families and supervise the rescue operation.

District police have registered a case against the bus driver and its operator for the deaths.

"We have booked a case of negligence and rash driving against the driver and bus owner to investigate the case. The bus operator has been summoned for the inquiry," Devaraj told reporters later at Mandya.

A 20-member team of the National Disaster Response Force (NDRF) and specialist divers joined the rescue operation to retrieve the bodies and lift the ill-fated bus from the canal.

"We have directed the river authority to stop the water flow to speed up the rescue work and lift the bus from the canal," said Puttaraju.

The man-made canal was built to supply the river water to agricultural fields in the district.