Six young firemen were killed on Tuesday as they battled a blaze engulfing a bowling alley in northern Taiwan, officials said.

The men, all in their 20s, were trapped and killed in a "sudden burst of flames", which caused the partial collapse of the building in Taoyuan county. Fire had broken out in the early hours of the morning, when the venue was shut.

Around 90 firefighters had been sent to the scene and two workers were rescued uninjured, the Taoyuan fire department said.

"There was a lot of smoke -- we decided that (our firemen) should stop going in and requested our colleagues to pull out, but they did not have time to evacuate during a sudden burst of flames," said fire department official Shih Shou-yang.

Taoyuan mayor Cheng Wen-tsan told reporters that the cause of the fire was under investigation and expressed his sadness over the loss of the firemen.

"Great sadness. Six firemen unfortunately died in the line of duty," Cheng wrote on his Facebook page.