Police Sgt. Alan Monks said most of the adults on the bus had been drinking heavily. An hour before the crash, police stopped the bus and arrested its original driver. They believe another driver -- also under the influence of alcohol -- took his place.

Police Sgt. Monk said: "We took the keys and believed that we had immobilised the bus. However, we understand there was a second set of keys on the bus."

BANGKOK – At least 24 people, most of them schoolteachers, were killed and 23 others seriously injured when a speeding bus ran off the road and plunged down a 100-meter (300-foot) ravine in northern Thailand, The Nation newspaper reported Sunday.

According to the English-language daily, the chartered bus tried to avoid a motorcycle that cut in front of it when the driver lost control and swerved off the narrow road Friday.

Eyewitnesses reportedly said the motorcycle had cut in front of the speeding bus to evade a dog.

The bus, carrying 47 passengers, was one of three taking schoolteachers andothers from Bangkok on a two-day sightseeing tour. The accident occurred in the province of Tak, 380 kilometers (235 miles) northwest of Bangkok.

Bus accidents with high fatalities are common in Thailand, where driver training is minimal and rules of the road routinely ignored. Many bus drivers are required to work long hours, and take amphetamines to try to stay awake.