(CNN) After Rep. Steve Scalise was shot in the hip at a Virginia baseball field on Wednesday morning, questions swirled around his condition.

The Louisiana Republican's office released a statement that morning that said he was "in good spirits" and spoke to his wife by phone before surgery. But MedStar Washington Hospital later said he had arrived in "critical condition" and remained so after surgery.

One of the questions surrounding Scalise's injury has to do with where he was shot. Although an injury to the hip might sound minor compared with other areas -- like the head or chest -- trauma doctors are not so quick to breathe a sigh of relief.

"When you tell me someone's shot in the hip, I have a whole different thought process," said Dr. Joseph Sakran , director of emergency general surgery at Johns Hopkins Medicine. "People think, 'It's their pelvic bone. It'll be fine.' "

In fact, the injury was far more serious,according to an update from MedStar Washington Hospital Center released Wednesday night by Scalise's office.

"The bullet travelled across his pelvis, fracturing bones, injuring internal organs, and causing severe bleeding," the statement said.

Stop the bleeding

After a gunshot wound like the one Scalise suffered, the main goal is to find the source of the bleeding and stop it, said Dr. Enrique Ginzburg , trauma medical director of the Jackson South Medical Center in Miami.

Ginzburg said he would be concerned about injuries to a major vessel, such as the iliac arteries, which supply blood to pelvic tissues and the legs, or the aorta, which is the largest artery in the body and runs from the heart to the lower abdomen.

Statements from Scalise's office have not identified which vessels were struck or which organs were damaged by the bullet.

"The reality is, it really depends on the trajectory" of the bullet, Sakran said.

At a certain angle, a bullet may hit the bladder, colon or small bowels, increasing the risk of infection down the line, he said. Still, bleeding is far more daunting.

"The number one, two and three cause of death in trauma is hemorrhagic shock ," Sakran said, referring to the fatal condition in which too much blood is lost for the heart to supply oxygen to organs and tissues. This sends the body into shock.

The bullet need not even hit a blood vessel directly in order to rupture it. A high-velocity bullet creates a shock wave around it, which can stretch and shear surrounding tissues . This process is called "cavitation" because it forms a cavity much larger than the bullet path itself.

The faster the bullet -- as with longer-barrel rifles -- the more damage that bullet can do, said CNN chief medical correspondent Dr. Sanjay Gupta.

Two firearms were recovered from the baseball field where Scalise was shot: an SKS rifle and a 9-millimeter handgun, according to a law enforcement source. Authorities believe that Scalise and three others were shot with the SKS rifle.

The most recent statement by Scalise's office anticipated that "he will require additional operations," though what types of surgery and the reason for them remain unclear.

With some injuries that have a high mortality rate, such as damage to the iliac vessels, trauma surgeons will often do an initial surgery -- known as damage control -- to keep a patient from bleeding to death, Ginzburg and Sakran said. Doctors may go back in later to do more complex repairs to any vessels, organs or bones that were damaged.

"Many years ago, we tried to do complete operations for extensive trauma patients, but what we found was that the patients did worse because we were trying to do too much in that single operation," Ginzburg said.

The number of units of blood Scalise required -- which the hospital has not revealed -- would be an indication of his overall prognosis, Ginzburg added.

"The more blood he lost, the more difficult the case," he said. "It's an indication of how critical the patient is."

A second chance

When Sakran was a senior in high school, he became a victim of gun violence himself. After a fight broke out at a football game, someone pulled out a weapon and fired into the crowd. Sakran was shot in the throat.

"I was really inspired to go into medicine to be able to give other people the same second chance that I was given," said Sakran, who grew up in Fairfax, Virginia, not far from Alexandria, where Scalise was shot.

Though it happened many years ago, his memories of being shot are most salient when he has to deliver bad news in the waiting room -- to the families of people he was not able to save.

"I know that what I'm about to tell them is about to change their world," he said.

"And it's heartbreaking, because a lot of this can be averted," added Sakran, who pursued degrees in public health and public policy in hopes of preventing shooting deaths on a larger scale.

Nearly 100 people die every day from firearms, according to Centers for Disease Control and Prevention data from 2014. Over twice that number are injured.

Even for those who survive a gunshot wound, the scars may be emotional as well as physical.

"There is also a lot of new data coming out on PTSD ... related to this kind of violence, and that can be lifelong," Dr. Bryan C. Morse , a trauma surgeon at Grady Memorial Hospital in Atlanta, previously told CNN.

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"I tell my patients, if you have a major gunshot wound, it will take you at least a year to get back to where you were before," he added. "And that's if everything goes well and you have a good support system at home."

Sakran said he benefited from supportive family and friends who were present throughout his recovery and who helped mold him into the surgeon and advocate he eventually became.

"I've been able to channel some of my past experiences into how I'm caring for patients now," Sakran said.

Correction: An earlier version of this story incorrectly described the SKS rifle.