Former Congresswoman Gabby Giffords and her husband are urging legislators to act in order to stop massacres like the one that happened last night in Las Vegas. Speaking on Capitol Hill, Captain Mark Kelly told reporters last night's attack is an example of a worst case scenario -- high-power weaponry in the hands of a determined killer with a tactical advantage. Kelly said Americans shouldn't accept rampant gun violence as simply the cost of living in America. Kelly called on Congress to stop legislation that will weaken gun laws and act to rein in the chaos. Giffords was at Kelly's side as he spoke, but she didn't speak herself. Giffords was shot in the head during an attempted assassination in Tucson in 2011 that left six people dead.