5 Things to Know This Morning

Dec. 4, 2013— -- Your look at the five biggest and most buzz-worthy stories of the morning.

1. Truck Carrying Radioactive Material Stolen in Mexico

A truck carrying cobalt-60, an extremely dangerous radioactive substance, was stolen in Mexico.

2. Newtown to Release 911 Calls From School Shooting

Recordings of 911 calls from the Sandy Hook Elementary School shooting are being released today.

3. Mandela Putting Up 'Courageous Fight'

Former South African President Nelson Mandela is not "doing well," according to members of his family.

4. Walker Autopsy Expected to Be Released Today

Authorities are expected to release the results of autopsies on "Fast & Furious" actor Paul Walker and his friend today who both died in a fiery crash.

5. Nigella Could Face Questions About Alleged Drug Abuse at Trial

Celebrity chef Nigella Lawson will testify in court today and could face questions about her alleged drug use.