DALIAN - Two people injured by a Sunday oil tank blast died in the hospital on Monday in northeast China's Liaoning province, the local safety watchdog said.

One tank containing residual diesel oil exploded on Sunday at a PetroChina outlet in the port city of Dalian, causing nearby tanks to burst into flames, firefighters with the city said.

Four people were at the site at the time of the accident, including two people who remain missing.

The storage tank hit by the blast was part of the PetroChina Dalian Petrochemical Company and was being renovated so production could resume later this year, according to an official at the company. PetroChina is the country's top oil and gas producer.

Environmental authorities said the sea nearby had not been polluted but some residential communities were affected by fumes. Oil barriers have been erected in the sea near the factory as a precaution, and the local government has advised nearby residents to close their windows.