At least five people are dead after a toxic gas leak in a workshop near the hangar of an airport in Urumqi, capital of northwest China's Xinjiang Uygur autonomous region, local authorities said Wednesday.

The accident took place at about 7:20 p.m. in a nitrogen-making workshop of a business near the Urumqi Diwopu International Airport, a spokesman with the Xinjiang Regional Work Safety Bureau said.

The five dead include business workers, airline's crew members and medical workers, the spokesman said.

An unspecified number of people are still under emergency medical operation, he said.

An initial investigation shows that the gas leak was caused by the worker's error in operation, he said.

Local authorities are further investigating the accident, he added.