At least 10 people were killed and 19 others injured in an explosion at a gas plant workshop in China's Yima city on Friday, local media reported.
So far 10 people are confirmed dead and 19 others seriously injured, official media broadcast on Saturday.
Five more people remain unaccounted for, state-run CCTV reported.
The incident happened around 6 pm on Friday and the injured were sent to the hospital, according to local officials.
The explosion did not involve tanks of dangerous materials, the local government said.
"The sound was extremely loud with a ball of fire and clouds of smoke in the air," a local resident, who was 500 meters away from the gas plant when the explosion occurred, was quoted as saying by the Beijing News.
"Customers who bought goods outside were hurt by broken glass," he said.
The factory was named as the first provincial-level enterprise to put in place a double prevention system for safety production risks in Henan this month.
The Yima gas plant of Henan Gas Co Ltd was established in 1997, covering an area of 87 hectares, with more than 1,200 employees.
It is listed as a key monitoring enterprise by the Ministry of Ecology and Environment.
Investigation into the cause of the accident is underway, state-run China Daily reported.