Three workers died and 23 others were hospitalized following a toxic gas leak at a chemical plant in southwest China's Guizhou Province between May 4 and 10, local authorities confirmed on Wednesday.

At least 26 workers were exposed to a serious release of arsinegas at Zhenpanjiang Chemical Plant in Dewo Town of Anlong County, in the Bouyei-Miao Autonomous Prefecture of Qianxinan, the provincial workplace safety watchdog said.

Doctors at the People's Hospital in Qianxinan diagnosed acute arsine poisoning.

People exposed to arsine gas, which has an odor like garlic, may not notice a reaction for several hours, a hospital source warned on Wednesday.

He said three victims had been too late in seeking medical attention. "One of them died on May 11 and the other two on May 14."

By Wednesday, three victims had been released from hospital and 20 people were being treated. Two of them were in critical condition, he said.

Local authorities have shut down the factory and investigation is continuing.

A similar accident in the same factory hospitalized three workers on March 30, the local government said.

Arsine is the most toxic form of arsenic, harmful even when ingested in even small quantities. The gas destroys red blood cells, which can lead to kidney failure. Exposure can cause chills, fever, dizziness, disorientation and abdominal pains.

Editor: Yan