GUIYANG -- The death toll of a bus fire that occurred in Guiyang, capital of southwest China's Guizhou province, on Thursday has risen to six.

The municipal authorities confirmed the death toll early Friday morning, adding there are 35 others injured in the accident. One of them is still in critical condition.

On Thursday, the municipal publicity department said five were killed in the fire and 35 others were injured.

The fire broke out at?12:37 pm Thursday in the Bus 237, when it was passing by a primary school in the northern part of Guiyang. The fire spread so quickly that many people simply did not notice the hammers positioned on the bus to smash windows in emergencies, according to the victims.

Authorities are still probing into the cause of the fire.

At least five killed in Guiyang bus fire	Deadly bus fire in Guizhou investigated