Photo taken on Feb. 25, 2021 shows a U.S. flag flying at half-staff in front of the United States Court House Building in Los Angeles, California, the United States. The California authority reported Thursday that the United States' most populous state had 50,991 deaths from COVID-19, about one-tenth of the U.S. total from the pandemic. The U.S. COVID-19 deaths surpassed the grim milestone of 500,000 on Monday as key indicators of virus transmission in the country have continued to fall, while emerging variants are causing fresh concerns. U.S. President Joe Biden ordered all U.S. flags to be flown at half-staff at all federal buildings and military posts in the United States and abroad. (Xinhua)