Published: Jul 30, 2010 11:50 PM EDT
Updated: Jul 30, 2010 7:42 PM EDT

LOS ANGELES, Cali. (AP) - An industrial building with a tampered gas line exploded Friday, killing a man who was hurled into the street and another who was electrocuted by a downed power line.

The blast turned the front of the wooden building in South Los Angeles into a mass of downed, shattered wooden beams. The building caught fire and 100 firefighters doused the blaze in about 25 minutes, fire spokesman Erik Scott said.

One of the victims died as he tried to move his stake-bed truck away from the building and was jolted by a downed 34,500-volt power line, fire Capt. Stephen Ruda said.

Daniel Ibarra, who works at the building, said he was taking out the trash when the blast hit. The 27-year-old man appeared in shock as he leaned against a wall with a bruised leg surveying the damage.

"I was very lucky," said Ibarra, whose thick black hair was singed on top.

An urban search-and-rescue team shored up beams and sent in dogs to search for another person after hearing reports that someone might be trapped in the debris. Ruda said the dogs detected nothing, but heavy equipment would be brought in to move the debris and continue the search.

The cause of the blast remained under investigation, but Ruda said it was suspected that natural gas or an industrial gas may have been leaking and collected overnight in the building then ignited when operations resumed in the morning.

The gas meter at the building was shut off Thursday, and someone installed an illegal line to the meter that allowed natural gas from a street line to enter at excessively high pressure, said Denise King, a spokeswoman for Southern California Gas Co.

The gas line bypassed the meter's shut-off valve and its regulator, which was designed to reduce pressure to safe levels, King said. She did not know why the meter had been shut off.

The business, J.L. Spray, has four employees and makes metal security fences, doors, windows and gates, said Elizabeth Alvarado, a secretary for the business.

She was not at the site when the blast occurred but said the owner, Jaime Lara, arrived every morning to start a propane furnace that is used to heat-cure a paint-like powder coating that is used on the metal.

Jonathan Apol, 20, a welder who works in a building next door, said he was putting on his work coveralls when he heard the explosion.

"I thought it was like an earthquake or something," he said.

He heard a bang followed by two more a few seconds later. He raced into the street in his boxer shorts and saw two dazed men standing in front of a burning building.

One man was shouting: "Jaime! Jaime!" Apol said.

Hours after the explosion, workers from neighboring businesses were still gathered outside the building where blackened wood beams had collapsed inward. Debris was strewn along the block, and some nearby cars had shattered windows.