Tianshui City, Gansu Province, northwest China - April 21, 2018 (CCTV - No access Chinese mainland)
1. Accident site on expressway
2. Burnt road sign
3. Burnt road surface
4. Various of workers clearing debris
5. Vehicles parked on expressway
6. Various of spill, debris
7. Various of damaged guardrail
8. Debris
9. SOUNDBITE (Chinese) Li Ling, deputy director, Tianshui Environmental Protection Bureau:
"We conducted continuous monitoring according to our monitoring plan. The air quality at the accident site and in the downtown area was up to the standard starting from 11:00."
10. Various of vehicles clearing debris
11. Amateur shots of truck on fire
12. Amateur shots of truck on fire, dense smoke

Debris has been cleared up and traffic has resumed after a truck carrying toxic chemicals caught fire on Saturday in northwest China's Gansu Province, killing one person, and injuring another.

The accident took place at 03:35 near the Qinzhou service area of the Shiyan-Tianshui Expressway, around 20 km away from Tianshui City of Gansu.

The truck carrying 41 tons of phosphorus pentasulfide was heading for Baiyin City of Gansu from Mianyang City of southwest China's Sichuan Province, when another truck running in the same direction crashed into it, causing a big fire.

The fire was put out at around 08:20.

Part of Tianshui was shrouded in smog as dust generated in the burning of chemicals spread.The density of sulfur dioxide exceeded 2,000 micrograms per cubic meter at about 09:00, according to an auto-monitoring station in the city.

As of 11:00, the local environmental authorities said that the air quality returned to normal.

"We conducted continuous monitoring according to our monitoring plan. The air quality at the accident site and in the downtown area was up to the standard starting from 11:00," said Li Ling, deputy director of the Tianshui Environmental Protection Bureau.

The local environment monitoring agencies collected water samples from four monitoring spots around the accident site, and found the density of total phosphorus was between 0.03 and 0.04 microgram per liter, lower than the national standard of 0.2 microgram per liter.

To guard against further spread of the hazardous chemicals, workers curbed and covered the spill with sand and cleared up the debris on the expressway.

The two-way traffic in the section of Tianshui South to Tianshui Town, which was cordoned off after the accident, was reopened at 22:00.

The injured person has been sent to hospital.

The cause of the accident is still under investigation.