An explosion at a chemical plant in Zhejiang Province that local residents demanded be shut down years ago left two workers injured Saturday.

The explosion occurred at around 8:50 pm at the Yue'an Chemical Plant in Panshi township, Yueqing, blowing up a boiler and causing colorless ammonia gas to leak, China News Service (CNS) reported Sunday.

"When I heard the huge explosion, I thought it was an earthquake," a local resident surnamed Zhou, who lived some two kilometers away from the site, told the Global Times Sunday.

"I rushed out of my house and saw huge flames in the direction of the plant. It was then that I realized there had been an explosion," Zhou said.

Minutes later, firefighters and police arrived and sealed off the site, extinguishing the blaze that had engulfed workshops and diluting the ammonia gas with water cannons.

An official surnamed Jin from the Yueqing Publicity Department told the Global Times Sunday that the two injured workers have been rushed to the Third People's Hospital for treatment, and their conditions were not life threatening.

A local villager surnamed Yuan said he had a "sleepless" night after the explosion.

"We used wet towels to cover our noses to prevent breathing in the pungent gas," the 50-year-old villager who lived one kilometer away from the plant said.

The blast sent a segment of the boiler flying and hit the walls of Yuan's neighbor's house, leaving a giant hole there.

"Fortunately for them, no one was home at that time," Yuan said.

Other households suffered broken windows and dented walls.

Some villagers, fearing further explosions and continued danger from the harmful gas, fled to the neighboring town.

"Most evacuated locals have returned to their homes," Jin told the Global Times Sunday afternoon. "The fire has been extinguished, the leakage blocked and the dilution process ended. A joint investigation carried out by the environmental protection bureau, security and fire control departments indicated there is no danger now."

Local resident Zhu Yi'an said one of his friends complained about his eyes becoming "swollen and inflamed" hours after the gas permeated the air.

"Hopefully the local government can quickly make public the detailed cause of the explosions, and be well aware of the security and pollution risks of locating chemical plants around our village," Zhu said.

Yuan recalled that about five or six years ago, some 500 local villagers called on the township government to close the plant, complaining that the pungent gas would cause long-term harm.

"However, they (local officials) wouldn't listen," Yuan said. "Hopefully, the plant can be closed down now."

Inhaling large quantities of ammonia in a short period of time results in symptoms including a sore throat, coughing, headaches, and difficulty in breathing. In serious cases, excessive amounts of ammonia in the blood could prove fatal, according to an article published by the Shanghai Pudong New Area Disease Prevention and Control Center.