Christopher Lorek and Stephen Shaw, the two FBI agents who died in a training accident on Friday off the coast of Virginia Beach, Va., were part of the bureau's Critical Incident Response Group.

According to the FBI, that unit:

"Consists of a cadre of special agents and professional support personnel who provide expertise in crisis management, tactical operations, crisis negotiations, hostage rescue, hazardous devices mitigation, critical incident intelligence, and surveillance and aviation.

The tragic deaths of 29 coal miners in a massive explosion in 2010 has provided new evidence of a resurgence of the disease known as black lung.

On Monday, a team of pathologists and lung disease experts will present the results of a detailed study of lung tissue from some of the victims of the Upper Big Branch mine disaster in West Virginia. They'll describe the findings at the American Thoracic Society's annual conference in Philadelphia this weekend.

Sales of guns and ammunition rose after President Obama took office in 2008, and they went through the roof starting late last year, when a school shooting led to a push for new gun control measures. That's led to a prolonged ammunition shortage, even with manufacturers running at full capacity.

Dick Trickle, a "short-track hero" in the '70s and '80s who moved to the NASCAR circuit later in his career, died Thursday.

According to The Charlotte Observer, the 71-year-old was killed by "an apparent self-inflicted gunshot wound, Lincoln County [N.C.] deputies said."