heat advisories are in place for more than 58 million americans. brittney griner s message to the white house. her letter to president biden, handwritten from a russian prison, terrified she might be there forever. and on this fourth of july, how freedom means something different to griner today. shark attack. a lifeguard playing the victim in a training drill is bitten by a shark. how he fought back. and, baseball for the social media generation it s driving fans bananas. this is the cbs evening news with norah o donnell, reporting from the nation s capital. garrett: good evening to our viewers in the west. thank you for joining us on this july fourth. i m major garrett, in for norah. tonight, at least six people killed and dozens more wounded in the nation s latest mass shooting. it targeted an independence day parade in suburban chicago. and some breaking news: the manhunt for the person of interest, 22-year-old robert e. cremo iii, is over. police say the gunman open