(ANSA) - ROME, DEC 10 - An operator raised the alarm seconds before Monday's explosion that killed five workers at an Eni fuels depot at Calenzano near Florence, investigative sources said Tuesday.
    It all happened at loading platform number 6 of the loading area which has 10 platforms, they said.
    At 10:21 and 30 seconds, the recorded time according to the investigators, an operator pushed the alarm button but in a few seconds there was the initial explosion, believed to have been caused by a spark igniting spilled fuel.
    This was followed by a chain of explosions involving at least five tankers, the investigators said. (ANSA).