Death toll from oil pipeline blast raised to 52

QINGDAO, China, Nov. 24 (UPI) -- The death toll from an oil pipeline explosion in northeast China was raised Sunday to 52, with 11 people still missing, officials said.

The Sinopec oil pipeline blast occurred Friday morning in the coastal city of Qingdao in Shandong province.

Six of those who died were professional firefighters, authorities told China's state news agency, Xinhua. Four of those killed in the blast have yet to be identified.

Rescuers were search for possible survivors Sunday, Xinhua said.

Sinopec Chairman Fu Chengyu apologized for the accident Saturday and vowed to cooperate with investigators to determine the cause of the blast.