``People were yelling and running for cover,'' Senghaas said. ``When our officers arrived, he was still shooting.'' The incident occurred about 7:40 a.m.
Amtrak spokesman Cliff Black identified the dead foreman as John M. Jenson, 41, of Newark, Del. Injured were foreman John Fedora, 38, of Secane, Delaware County, and electrician John Morrison Jr., 34, also of Newark.
Fedora and Morrison were listed in critical condition at Christiana Hospital with multiple gunshot wounds.
The shootings took place in a huge diesel-maintenance building on the rail yard grounds. Black said Herr had worked for Amtrak since 1976.
Senghaas said two Wilmington police officers, Patrolman Michael Lawson and Sgt. John Randolph, arrived at the rail yard in response to a 911 emergency call within minutes after the first shots were fired.
She said workers directed the officers to the building, where they spotted Herr on a catwalk about 25 feet above the ground. When Herr turned and aimed his gun at Lawson, the officer fired once with a 12-gauge shotgun, and Herr fell to the ground. He was pronounced dead at the scene.
Senghaas said Herr fired at least 15 rounds during the spree. She said Lawson would be temporarily transferred to desk duty, pending a routine internal investigation.
It was unclear yesterday whether Jenson or Fedora ever supervised Herr. But a union official said both men had complained to supervisors about Herr's mental state.
James Riley, president of the Transportation Workers Union of America, Railroad Division 2015, said Herr had long been known as ``pigeon man'' because he would talk to the pigeons flying around the cavernous Amtrak repair shop.
``This guy, he'd talk to the walls. He'd apparently talk to the sky. He wasn't stable,'' Riley said. ``He must have snapped.''
Riley, who was in the repair shop when the shooting started, said Herr walked from the back of the vast shop toward the front, spraying bullets randomly.
Police declined to say whether they had established any motive.
The facility repairs and maintains electric and diesel locomotives and employs about 450 people. About 70 were on the job when the incident occurred. The facility was closed yesterday but was expected to reopen this morning.
Amtrak chairman Thomas M. Downs said in a statement: ``I am shocked and saddened by this violent act, and my heartfelt sympathy goes to the victims and their families.''
* To see video of the scene of the shooting and an interview with an eyewitness, visit The Inquirer's site on the Internet: http://www.phillynews.com