The steel mill, located at Tadipatri in Andhra Pradesh, belongs to Brazilian firm Gerdau

Six workers died in a poisonous gas leak at a private steel mill rolling unit in Anantapuram district today, police said.

District Superintendent of Police G Ashok Kumar told PTI over phone that the mishap occurred while testing was being done after maintenance work in the unit.

"As per preliminary information, two workers died on the spot and four others in hospital. Carbon monoxide is the main gas used for reheating process and its leak caused the mishap," the police officer said.

There was no clear information about injuries to other workers, he said, adding rescue operation was being carried out.

The steel mill, located at Tadipatri, belongs to Brazilian firm Gerdau, a leading producer of long steel in the American sub-continent.

Andhra Pradesh deputy chief minister (Home) N China Rajappa expressed grief over the deaths.

