About 700 people are still displaced after experts failed to cap a leaking gas well for a second time in southwest China's Sichuan Province, local officials said on Thursday.
The leak occurred last Thursday during drilling. Over 12,000 residents nearby were evacuated after the leak.
The first attempt to cap the well was carried out on Monday but failed.
Most of the 12,000 residents have returned home after local environmental protection authorities said no toxic chemicals were detected in the air. About 700 of them are yet to return because their houses are within 500 meters of the well.
The second attempt on Wednesday initially was thought to be successful. However, it leaked again and emergency crew had to re-ignite the leak an hour after they completed a second capping operation.
An official with China Petrochemical Corporation, the owner of the well, said that engineers are working on a new capping plan, which may come out on Thursday.
No casualties have been reported in the gas leak, according to local officials.