The base was put on lockdown, as Army officials took to Twitter and Facebook to alert soldiers there to shelter in place and stay away from windows. HOUSTON: As many as four people were killed and 14 were wounded after a gunman in uniform opened fire at Fort Hood on Wednesday, shutting down the sprawling Army base and inciting a huge police response, a member of Congress said. The shooting echoed the deadly rampage carried out there in 2009 by an officer who turned on his fellow soliders. Officials at Fort Hood released few details about the shooting but said that it appeared that the gunman was among the dead. Reports of the shooting sent dozens of local, state and federal law enforcement officials rushing to the base in Killeen, Tex., as they had back in November 2009. A spokeswoman for the FBI in San Antonio said agents in that office were part of the response on Wednesday. Representative Michael McCaul, Republican of Texas, the chairman of the Committee on Homeland Security, said that as many as four people had died in the attack, including the gunman. On a conference call with reporters, McCaul said the authorities had identified the suspect as Ivan Lopez but that a motive for the shooting remained unclear. The shooter was wearing an Army uniform, but it was unclear whether he was on active duty, McCaul said. In Chicago, President Obama described the shooting as a fluid situation that White House and Pentagon officials were closely following. "We are going to get to the bottom of exactly what happened," the president said. "We're heartbroken something like this might have happened again." The chairman of the Joint Chiefs of Staff, Gen. Martin Dempsey,said that many questions remained but that their focus was on supporting the victims and their families. "This is a community that has faced and overcome crises with resilience and strength," he said in a statement. The episode appeared to have unfolded around 4:30pm at a medical support building on the base. Witnesses described chaos as gunshots rang out. "It was like if you went into a room and turned on the lights â€” all the bugs just scattered," a man who would only identify himself as Tyler said in an interview with KCEN, an NBC affiliate. After the shooting, he described seeing men, women and children being escorted out of a building at gunpoint. The base was put on lockdown, as Army officials took to Twitter and Facebook to alert soldiers there to shelter in place and stay away from windows. The injured were being transported to Fort Hood's medical center and other area hospitals. Scott and White Memorial Hospital in Temple, Tex., said it received four patients and expected more. The victims' conditions ranged from stable to "quite critical," and the injuries included gunshot wounds to the abdomen, chest and neck.Traffic at the main gate of the base was at a standstill, as the authorities scanned exiting vehicles and blocked cars from coming onto the base. A Central Texas College campus four miles away was also placed on lockdown. In Washington, American intelligence officials said they were investigating any potential terrorist connections to the shooting, but so far had no evidence to suggest that. The heightened alert brought back memories of the previous shooting at Fort Hood that many at the base had to struggle to overcome. On November5, 2009, Maj. Nidal Malik Hasan opened fire inside the Soldier Readiness Processing Center, shooting unarmed soldiers and commissioned officers as they tried to hide under desks and tables. Major Hasan, a Muslim military psychiatrist, shot and killed 12 unarmed soldiers and one civilian while wounding or shooting at 30 other soldiers and two police officers. Prosecutors said one of his motivations was to kill as many soldiers as he could to wage jihad on American military personnel. A Senate report called it the worst act of terrorism on American soil since Sept. 11, 2001. After a military trial that was held at the base last year under tight security, a jury of 13 senior Army officers found him guilty and sentenced him to death.