US Heatwave (Image source: AP)A severe heat wave that gripped large parts of the United States during the country's 250th independence day celebrations has claimed the lives of more than two dozen people, with soaring temperatures triggering health emergencies.Several public events, including an Independence Day parade in the US capital, were also cancelled because of the dangerous weather conditions.New Jersey records highest death tollNew Jersey was among the worst-hit states, with at least 29 heat-related deaths reported across 10 counties, according to the state's department of health.Officials said most victims were found in homes without air conditioning, while both elderly residents and younger adults were among the fatalities."Extreme heat is the number one weather-related killer i