Flags to be flown at half-staff in multiple US states on Sunday.

Flags are being flown at half-staff across the US for two reasons. Firstly, to honor the National Fallen Firefighters Memorial Service, which is held annually in Emmitsburg, Maryland, and secondly, to honor the victims of the mass shooting in Allen, Texas, which left eight people dead and seven injured. President Joe Biden has ordered US flags at all federal buildings and grounds, military posts, naval stations, and naval vessels to fly at half-staff until sunset on Thursday, May 11.