A fire raged through a four-story building crowded with weekend shoppers and diners today in northwestern South Korea, killing at least 54 people, many of them teenagers, police said. It was the country's worst fire in 25 years.

{lcub}Authorities suspect the blaze was started by electric sparks from a broken light bulb that fell onto a can of paint thinner in an underground karaoke bar. Police questioned four electricians who had been doing renovations in the bar, but released them early Sunday.{rcub}

Seventy people were injured in the fire. Police reduced the death toll from 57, but said it may rise again because some of the injured people were in critical condition.

The fire broke out around 7 p.m. in Inchon, South Korea's third-largest city, 30 miles west of Seoul. The blaze gutted the building packed with restaurants, karaoke clubs, a beer bar and billiard room.

Most of the victims were teenagers or in their early twenties, police said.

Fire engines rushed to the scene and extinguished the fire in 40 minutes, police said.

Most of the dead were found in a second-floor beer bar and third-floor billiard room, police said.

"The fire spread so quickly that by the time we got into the beer bar, we found many people already dead. They appeared to have suffocated from the smoke," said local police chief Park Myong Hwan.

The fire is the worst since a hotel fire killed 88 people in Seoul in 1974.