Details on the dangers of Rep. Steve Scalise's injuries

NEW YORK -- House Majority Whip Steve Scalise, who was critically wounded during a baseball practice shooting in Virginia, underwent his third surgery on Thursday. 

CBS News chief medical correspondent Dr. Jon LaPook spoke with Scott Pelley on "CBS Evening News" about the nature of the congressman's injuries. 

"We know that the bullet entered his left hip," LaPook said. "It went across the pelvis, causing fracturing of the bone and causing damage to internal organs."  

LaPook went on to explain that bone fragments caused by fractures "can act almost like a shrapnel and wreak havoc" on the body, causing serious damage due to the amount of organs that are packed into a small area. 

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CBS News chief medical correspondent Dr. Jon LaPook goes into detail about the nature of Rep. Steve Scalise's injuries.

CBS News

During their conversation, Pelley noted that the congressman was transported in shock to a medical center. 

"Shock means there's too little blood flow to major organs, like the brain, the kidneys, the lungs," LaPook said. "And that can cause damage to these organs."

Scalise's body most likely entered a state of shock because "a blood vessel or blood vessels were damaged when the bullet" entered his pelvic area, according to LaPook. 

The congressman was one of four people who were shot when 66-year-old James T. Hodgkinson, of Belleville, Illinois, opened fire on Republicans practicing for a charity baseball game against a team of Democrats. He remained in critical condition Thursday.