Four more bodies were recovered and another injured passenger died in hospital after a bus plunged into a river in southwest China's mountainous Guizhou Province on Tuesday, bringing the death toll to 19.

The other 13 injured are being treated in the People's Hospital in Renhuai City, local government authorities said.

The accident happened at about 2:30 p.m. when the bus traveling from Chishui City to Zunyi City plunged into the Chishui River in Renhuai City, Guizhou.

An initial investigation found there were 33 people aboard the bus when it left Chishui. However, it was not clear if any disembarked or got on during the journey.

According to Chen Yuzhong, head of the Renhuai publicity and information department, the bus was completely submerged as the river section was very deep. This increased the difficulty of rescuing the remaining passengers whose number remained unknown.

A rescue team arrived at the site for the operation and an investigation into the accident was underway.

It is not immediately known that if the tragedy was weather-related, but Guizhou has been one of the worst-hit provinces by snow and sleet that began from mid-January. Many roads have been cut off and power lines destroyed.

In another traffic accident, five people were killed and 26 others injured in a massive expressway pileup involving 13 vehicles in Mojiang, a county inhabited by people of Hani Minority in the neighboring Yunnan Province in the wee hours on Monday.

As of 3:30 a.m. Monday, all the injured were sent to hospital. Eight of them were seriously injured, and one remained in critical situation on Tuesday.

Tuesday marks the end of the country's weeklong Spring Festival holiday, a time when many travelers are returning to their place of work.

Chinese travelers made an estimated 235 million bus trips during the weeklong Spring Festival holiday, the Ministry of Communications said on Tuesday.

The figure represents a 3.4 percent rise from the same period last year despite the worst winter storms in half a century leading to highway congestions in many parts of the country.