UPDATE: President Donald Trump on Wednesday said the shooter who perpetrated the GOP congressional baseball practice attack is dead.
The incident injured five people injured, including House Majority Whip Steve Scalise.
"Authorities are continuing to investigate the crime and the assailant has now died from his injuries," Trump said from the White House.
WASHINGTON (CNN) -- Rep. Steve Scalise, a congressional staffer and members of the congressional police force were shot Wednesday morning in Alexandria, Virginia, in what sources are calling an apparent "deliberate attack."
Scalise, the third ranking member of House Republican leadership as the majority whip, appeared to have been shot in the hip and it appeared two Capitol Hill police agents were shot, according to Rep. Mo Brooks, who told CNN he was on deck when the shooting occurred. A congressional staffer was also injured.
Law enforcement has identified the shooter as James Hodgkinson of Belleville, Illinois, according to a federal law enforcement sources. Hodgkinson is 66.The shooter's injuries are described as serious, according to the law enforcement source.
As of 9:45 a.m. ET, Scalise was in stable condition but undergoing surgery, according to a statement from his office.
"Prior to entering surgery, the whip was in good spirits and spoke to his wife by phone," the statement said. "He is grateful for the brave actions of U.S. Capitol Police, first responders and colleagues."
The shooting took place at a practice for the GOP congressional baseball team. According to both congressional and law enforcement sources, the shooting appears to be a "deliberate attack."
In a statement, Texas Rep. Roger Williams, one of the team's coaches, said one of his staff members, legislative correspondent Zack Barth, was shot during the incident and is receiving medical attention. Williams tweeted Barth was "receiving medical attention but is doing well and is expected to make a full recovery."
The Capitol Police officers who were injured are "in good condition and have not suffered any life-threatening injuries at this point," Capitol Police Chief Matthew Verderosa said at the news conference.
Two law enforcement sources told CNN the shooter, who is in police custody, has been taken to a hospital.
It's too early to tell whether the shooting was an act of terrorism or whether members of Congress were specifically targeted, Tim Slater, the FBI special agent in charge, told reporters at a Wednesday morning news conference.
"It's too early to say. It's really raw at this moment," Slater said.
Members of Congress were practicing for a game that was scheduled for Thursday night at Nationals Park. It was not immediately clear whether it would go on as scheduled. The annual game has been played since 1909.
Lawmakers describe a chaotic scene
Lawmakers who spoke at the scene to reporters described a normal morning practice, at a field where they've practiced for years, when all of a sudden shots rang out. Lawmakers, staff members and even the young son of one of the members ran for cover, jumping into dugouts and over fences to avoid the gunshots.
Members described Scalise dragging himself roughly 15 yards away from second base, where he had been playing, and lying there until the shooter was neutralized, at which point some of them ran to assist him and apply pressure to the wound until he could be evacuated. Once they were able, Sen. Jeff Flake said he and Rep. Brad Wenstrup, who is a physician, went out to where Scalise was lying to apply pressure to the wound. Scalise was coherent the whole time, Flake said.
Kentucky Sen. Rand Paul told CNN "it would have been a massacre" without Capitol Hill Police.
"Nobody would have survived without the Capitol Hill police," Paul said on CNN. "It would have been a massacre without them."
"We had nothing but baseball bats to fight back against a rifle with," Brooks said.
Arizona Sen. Jeff Flake added that he saw a member of Scalise's security detail return fire on the gunman for what felt like 10 minutes, even though the police officer was wounded in the leg.
"50 (shots) would be an understatement, I'm quite sure," Flake said when asked about the total amount of gunfire, including police returning fire.
Brooks said the shooter appeared to be a white male but added that "I saw him for a second or two." He said the shooter was behind the third base dugout and didn't say anything.
"The gun was a semiautomatic," Brooks said, adding that he was sure it was a rifle but unsure what kind. "It continued to fire at different people. You can imagine, all the people on the field scatter."
Capitol Hill increases security, cancels events
The news of the shooting reverberated on Capitol Hill, where security was increased and regular proceedings were canceled or postponed.
The House decided to not hold any votes on legislation Wednesday, and many hearings were delayed. The House Natural Resources Federal Lands Subcommittee also canceled a scheduled meeting to debate gun legislation.
Capitol Hill Police notified congressional offices that the security presence on the Hill would be increased "out of an abundance of caution."
President Donald Trump also canceled an afternoon event at the Department of Labor.
Virginia Rep. Dave Brat told CNN that he learned of the news in the gym, and that members were all standing by for more information as the news unfolded.
The Sergeant at Arms of the House of Representatives, Paul Irving, is scheduled to brief House members on Capitol Hill in the 11 a.m. ET hour.
Trump tweets on the incident
The President is monitoring the situation, the White House said in a statement.
"The Vice President and I are aware of the shooting incident in Virginia and are monitoring developments closely," Trump said in a statement. "We are deeply saddened by this tragedy. Our thoughts and prayers are with the members of Congress, their staffs, Capitol Police, first responders, and all others affected."
Trump subsequently tweeted, "Rep. Steve Scalise of Louisiana, a true friend and patriot, was badly injured but will fully recover. Our thoughts and prayers are with him."
House Speaker Paul Ryan and Republican Majority Leader Kevin McCarthy are safe on Capitol Hill and receiving updates, aides tell CNN. Neither was at the practice.
Scalise is the first member of Congress to be shot since former Arizona Rep. Gabby Giffords was shot in January 2011. Giffords was shot in the head by Jared Lee Loughner at a "Congress On Your Corner" event at a Tucson grocery store. Giffords, who authorities said was the main target of the shooting, survived the attack but six others were killed and an additional 12 were injured.
Loughner pleaded guilty in 2012 and was sentenced to life in prison without the possibility of parole.
This story is breaking and will be updated.
CNN's Phil Mattingly, Dana Bash, Deirdre Walsh, Eugene Scott, Peter Morris, Karl deVries and Noa Yadidi contributed to this report.
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