Three of Discovery Channel's Storm Chasers were killed in the latest Oklahoma tornado. Tim Samaras and Carl Young, and Tim’s 24-year-old son Paul, were lost during Friday, May 31, 2013’s tornado outbreak, making the first time researchers were killed while chasing tornadoes.

The Discovery Channel team Tweeted their condolences.

You can see pictures of Tim, Carl and Paul at the Discovery Channel website, as they remember the three men who risked their lives to do what they loved.

10 people were killed in Friday's twisters.

Hear Tim Samaras' last telephone call before being killed in the tornado.