Dr. Jack Sava, the director of trauma at the MedStar Washington Hospital Center, said this afternoon that Scalise had "sustained a single rifle wound that entered in the area of the left hip. It traveled directly across towards the other hip in what we call a trans pelvic gunshot wound. The round fragmented and did substantial damage to bones, internal organs and blood vessels.
"I understand he was awake on scene but by the time he was transported by helicopter to the MedStar trauma center, he was in shock," Sava said. "When he arrived, he was in critical condition with an imminent risk of death."
Now, doctors are "encouraged in the improvement in his condition in the last 36 hours," Sava said. "We have controlled his internal bleeding and his vital signs have stabilized."
He refused to detail Scalise's injuries, but said that he would guess there are "hundreds of fragments" in Scalise and he has "no intention to remove all bullet fragments at this point" due to the high risk of looking for them.
Scalise has had two surgeries and will require additional operations, Sava said, adding that it's difficult to predict how long he will be in the hospital.
"He will certainly be in the hospital for a considerable period of time," he said. "Presumably weeks."
He said that Scalise has been mostly sedated but they've been able to turn down his medication enough for him to respond to family members. Sava said Scalise "clearly knows" his family is there and "appreciates" their presence.
Brett Horton, Scalise's chief of staff, read a statement from Scalise's wife today, thanking everyone "for the incredible amount of prayers and warm wishes we've received since Wednesday's events."
"We are especially appreciative of the strong outpouring of love and support from our neighbors, friends, from across Louisiana and across the country, as well as President [Donald] Trump, Vice President [Mike] Pence and all of Steve's colleagues who have reached out during this challenging time," the statement said. "Most importantly, we are forever grateful for the heroism of [Capitol Police officers] Crystal Griner and David Bailey, who saved everyone's lives at the baseball field that morning, including Steve's."
Griner, who was also shot, is in the hospital in good condition and spirits after a gunshot wound to the ankle, Sava said today.
Trump, in Miami this afternoon delivering remarks on Cuba policy changes, said of Scalise, "Because of him and the tremendous pain and suffering he's now enduring -- he's having a hard time, far worse than anybody thought -- our country will perhaps become closer, more unified. So important. So we all owe Steve a big, big thank you."
Former President George W. Bush wrote on Instagram today, "Last night I had a nice chat with Jennifer Scalise, who reports that Steve is fighting hard and getting better. They are both staying #ScaliseStrong, and Laura and I are praying for the Congressman's full and speedy recovery."
Trump today praised the police officers who fired back at the suspect after the gunfire broke out, saying, "Our police officers were incredible, weren't they? They did a great job."
Trump asked that all of the victims stay in people's prayers, adding, "Let us all pray for a future of peace, unity and safety for all of our people."
The alleged shooter, identified by police as James Hodgkinson, 66, of Belleville, Illinois, was killed in a shootout with police Wednesday morning after shooting Scalise, Griner and two others. Hodgkinson's wife emotionally told reporters Thursday, "I can’t believe he did this," saying there were no signs.
ABC News' John Parkinson contributed to this report.