Slain suspected Washington Navy Yard gunman Aaron Alexis suffered from "anger management problems" his family feared was linked to participating in rescue attempts of Sept. 11, 2001 victims, according to a police report obtained by the Herald.

Alexis told a Seattle cop in 2004 that he suffered from a "black-out" fueled by anger when he shot out the tires of a construction worker's car, according to a police report.

"He explained how he perceived (the victim) had disrespected him and how that perception lead (sic) to what Alexis described as a 'black-out' fueled by anger. He said he didn't remember pulling the trigger of his firearm until about one hour later," the report says.

Cops say Alexis shot out the rear tires of a construction worker's vehicle in May 2004 with a Glock 30, then went back into his home and did not answer the door when responding officers arrived. Police continued investigating, however, and arrested him on charges of malicious mischief in early June 2004.

"Alexis also told me how he how he was present during the tragic events of September 11th, 2001 and how those events had disturbed him," the report states. Police added Alexis' father told him "his son experienced anger management problems that the family believed (were) associated with PTSD. He confirmed that his son was an active participant in rescue attempts of Sept. 11, 2001." The report does not state where he was involved in 9/11 rescue attempts, but his family is from New York City, according to the Navy.

Police say Alexis was shot dead in today's "horrific" ambush at the Navy yard that left 12 other people dead and as many wounded.

The Navy said in a release that the 34-year-old left the Navy on Jan. 31, 2011, as a petty officer 3rd class. It's not immediately clear why he left. Alexis had been working for the fleet logistics support squadron No. 46, in Fort Worth, Texas.

Secretary of the Navy Ray Mabus said on CNN this evening that Alexis was a military contractor, specializing in computer technology.

The District Attorney's Office in Forth Worth released the following statement today: "Aaron Alexis was arrested on Sept. 4, 2010, by Fort Worth police on accusations that he recklessly discharged a firearm inside the limits of a municipality, a Class A misdemeanor. It was determined that Alexis was cleaning a gun in his apartment when it accidentally went off. A bullet entered an apartment upstairs. No one was injured. After reviewing the facts presented by the police department, it was determined that the elements constituting recklessness under Texas law were not present and a case was not filed."

The FBI is asking for the public's help on Alexis and his recent activity.

“No piece of information is too small,” said Valerie Parlave, assistant director of the FBI in D.C. “We are looking to learn everything we can about his recent movements, his contacts and his associates. We ask the public to look at the photos of the deceased shooter.”

President Obama said earlier today investigators will work tirelessly to ensure "whoever carried out this cowardly act is held responsible." The shooting was less than 4 miles away from the White House.

Probably a dozen more people were wounded — many still in surgery — in the attack and police said they have ruled out one man as being linked to the shooting but are still seeking a third person. That man is described as a black man in his 50s standing about 5-feet, 10-inches tall wearing olive-green military garb.

Metropolitan police Chief Cathy Lanier said one D.C. police officer underwent surgery and is in stable condition after he was shot at the yard.

City Mayor Vincent Gray said a shooter entered Building 197, which is where the Naval Sea Command is located, and opened fire around 8:20 this morning. Gray and other officials said a motive is not yet clear, but they do not suspect any terrorist link.

"As far as we know this is an isolated incident. We don't know of any other installments that are involved. We would ask all the residents to stay out of the area," the mayor added. "This is a horrific tragedy. The worst in recent history."

The U.S. Senate was shut down and tonight's Washington Nationals baseball game against the Atlanta Braves has been postponed until tomorrow.

Eyewitness accounts tell of a chilling scene when the gunman opened fire in a cafeteria, using weapons that included an AR-15 assault rifle and a shotgun, according to one report.

Patricia Ward, who works at the Navy Yard, said she heard three shots "pow, pow, pow" and then four more shots after a pause.

"Everybody was panicking and trying to decide which way to get out," Ward told reporters.

Security guards told people to "run, run, run," Ward said.

Boston police tell the Herald today they are monitoring the situation. Workers in the Navy yard were ordered to "shelter in place" — the same order given on April 19 during the manhunt for marathon bombing suspect Dzhokar Tsarnaev.

Chris Amon, ATF spokesperson, also said the same Virginia-based special response team that was activated for the Boston Marathon bombings was activated for the Navy Yard shooting.

Amon said the Virginia team is one of five SRT teams around the country, and has 145 full- and part-time members.

"They have active shooter training," Amon said. "They all train together once every three months. They train for these types of scenarios."

Amon said the team's day-to-day duties are to assist field agents as they deliver warrants to potentially dangerous recipients.

Janis Orlowski, chief medical officer at MedStar Washington Hospital Center, said in an afternoon press briefing that three patients, including one metropolitan police officer, were being treated at the hospital for gunshot wounds and were alert and responsive.

"They do have severe injuries, but we've been able to speak with a lot of them," Orlowski said. "They have not been able to give us any information regarding what happened to them. Obviously they're in pain and in distress because of what happened this morning."

Orlowski said one man suffered multiple gunshot wounds to the legs, one woman was shot in the shoulder, and another woman was shot in the hand and head.

"We have three individuals and we are told to expect more," Orlwoski said.

Orlowski said some of the weapons used "had to be a semi-automatic" because of the rapid-succession gunshots that witnesses reported hearing.

Professor James J.F. Forest, former director of terrorism studies at the U.S. Military Academy, said for the shooter or shooter to get onto the property they would have to show a security guard a valid military I.D. or military approved civilian or contractor's I.D.

"The I.D. could have been a stolen I.D. or a fabricated I.D. We don't know," Forest said.

He said the shooter or shooters could have come in by car, but the car would have to show a security sticker on its windshield indicating it was registered for base access and a minimum, the driver would need some form of official clearance.

"It's possible to get on base if a security guard is relatively benign and just checks the driver's ID and waives them through," Forest said.

Developing …

Dave Wedge, John Zaremba and Herald Wire services contributed to this report.