Safety experts for BP PLC warned their bosses of the potential for a "major site incident" more than two years before an explosion at the company's Texas City refinery killed 15 people and injured another 170, according to a broadcast report.

CBS' "60 Minutes" also reported Sunday that the Texas City plant manager, Don Parus, told his bosses in the company's London headquarters that most workers at the refinery felt the plant was unsafe.

According to CBS, one worker wrote, "This place is set up for a catastrophic failure." BP's top refinery executive, John Manzoni, has said under oath he didn't know of serious safety concerns until the explosion.

"They didn't do much," said Brent Coon, an attorney representing several victims suing BP. "Two months later the plant blew up."

The explosion occurred when faulty sensors did not warn of gathering vapors near the isomerization unit, which boosts the level of octane in gasoline. The vapors ignited as the unit was starting up.

The U.S. Chemical Safety and Hazard Investigation Board, one of several agencies investigating the blast, concluded the unit had a history of problems and was not hooked up to a flare system that burns off vapor and could have prevented or minimized the accident.