Two workers were killed and several injured when a crane collapsed at the National Art Gallery construction site on Coleman Street on Monday morning.<br /><br />Reports said the crane was lifting a mini excavator at around 10.30am when the boom suddenly collapsed.<br /><br />The boom and excavator fell to the ground, while concrete slabs attached to the rear of the crane came loose and fell on to scaffolding below.<br /><br />The two workers were pronounced dead at the scene by trauma paramedics, according to the Singapore Civil Defence Force (SCDF).