By Lester Holt, NBC News anchor
Up until this weekend the talk among weather forecasters was what a quiet spring this has been. Now they're talking about how many tornadoes broke out in the South in just one day yesterday. Dr. Greg Forbes, severe weather expert for our sister network, The Weather Channel, says based on the preliminary reports still coming in, he currently estimates there were about 30 tornadoes yesterday. The most staggering number however is 10. That's the confirmed number of people killed in Mississippi. There were also dozens of people hurt. Our team on the ground there today has heard some incredibly poignant stories of loss and survival, and we will have full coverage from there on Nightly News tonight.
There is also news from the destroyed oil rig off the coast of Louisiana. After first hoping they had dodged a major environmental disaster, officials are facing a steady leak of oil into the ocean. Our environmental affairs correspondent Ann Thompson is in the region tonight to tell us what happens now.
By now you may have heard about the homeless man here in New York who lay dying in a street from stab wounds as bystanders walked and passed around him. His death is especially tragic because the man was stabbed while coming to the aid of a woman who was being attacked. What about those who ignored him when he was in need? Jeff Rossen has spoken to human behavior experts about something called "the bystander effect," which may explain something that seems to defy explanation to most of us.
I hope you can join us for Sunday edition of NBC Nightly News.