LUSAKA, Zambia

A fire at an offshore Angolan oil platform left 17 injured Tuesday, with four in serious condition, said authorities.

The fire at Chevron's deep water Benguela Belize Lobito Tomboco (BBLT) occurred in the basement of the multi-story drilling production platform in the Block 14 concession, 97 kilometers (60 miles) offshore of the Cabinda coast.

"The cause of the fire, which broke out in the early hours of the day, is currently under investigation; all of them (17) are now on land and receiving appropriate medical care," the Angolan National Agency for Petroleum, Gas and Biofuels said in a statement.

Chevron said the incident occurred at a time when the platform was undergoing annual maintenance as part of a scheduled shutdown, with production halted May 1.

"The fire broke out at around 3 a.m. (0200 GMT) and all personnel have been accounted for," it added.