Of those killed, 14 are men, 10 are women and two are children, Colonel Marco Antonio Hadathy, fire chief in the city of Ibarra, told AFP by telephone.

The bus was traveling between Ibarra, 120 kilometers (75 miles) north of Quito, and San Lorenzo when the driver apparently lost control of the vehicle, which slammed into a hillside.

The bus then plunged head first into a ravine some six meters deep, Hadathy said.

"The impact was so powerful that the passengers were all piled up in the bus cabin," said Hadathy.

The dead were moved from the crash scene to a morgue in Ibarra, and the injured are being treated in three local hospitals, the fire chief said.

Fernando Castillas, a civil defense official, told AFP the accident was likely caused by the driver's error.

"Apparently the driver was speeding, and since it has rained, he lost control of the vehicle and drove it into the ravine," said Castillas.

It was the worst road accident in Ecuador so far this year.

At least 5,150 people died in traffic accidents in Ecuador last year, twice as many as in 2010, according to Inter-American Development Bank figures.

Ecuador sees the second highest number of traffic accidents in Latin America per 100,000 residents, after Paraguay.