BEIJING - The Ministry of Public Security on Thursday urged police to "resolutely carry out" road safety checks and traffic management in the wake of deadly accidents ahead of Spring Festival, when hundreds of millions will be rushing home.

By Thursday, the death toll from Wednesday's bus accident, in which a vehicle carrying 57 passengers veered off a highway bridge in Southwest China's Guizhou province, had risen to 18.

Among the 40 injured, six are in critical condition.

According to the ministry, the country this year has already seen half a dozen accidents in which five or more people were killed, and another two accidents that killed more than 10.

The ministry urged police forces to be deployed as much as possible on sections of roads where accidents tend to occur to check violations including speeding, overloading and fatigued driving.

Such checks will be carried out on long-distance coaches, vehicles carrying hazardous goods and school buses.

The ministry asked transportation companies to check the vehicles that will be used during the Spring Festival for potential safety hazards and has also asked the police to cooperate more closely with meteorological agencies.

An official surnamed Liu with the traffic management bureau under the ministry said pressure is especially high as a new season of Spring Festival travel is set to begin on Jan 8.

"We put prioritized management forces wherever they are needed, and wherever there are heavy traffic flows," she added.

An investigation team led by the ministry is still probing the cause of Wednesday's accident in Guizhou. The 53-seat bus with 57 passengers aboard, including four infants, fell off the icy bridge and into an 8-meter-deep crevice at about 6:30 pm.

Li Dengwen, head of Guizhou Meteorological Station, said freezing rains and snow are especially adverse to road transportation.

"Road surfaces tend to freeze at low temperatures in sections such as tunnel exits, bridges in cold air and at high altitudes," said Li.

He added that weather conditions before Jan 10 are not favorable for a new round of freezing rains - which quickly turn to ice on road surfaces.

"We inform traffic management authorities and police about freezing rains or sharp drops in temperature two to three days in advance."

"In emergency cases, we have a mechanism to immediately inform radio stations and telecommunication companies that send clusters of instant messages to the province's mobile phones."

Publicity officials of traffic divisions under the Guizhou public security bureau refused to answer what measures they have taken in response to the ministry's call.

More than 10,000 traffic police in East China's Jiangsu province have been organized to safeguard traffic since the beginning of this year, local police said.