Bill Phillips, an engineer with Jacobs Engineering who has worked for NASA for about 12 years, barricaded himself inside the building Friday, after managing to sneak a revolver past security at the sprawling space centre campus, police and NASA officials said.

 Phillips shot David Beverly in the chest, killing the NASA employee, and later shot himself in the head inside Building 44, a communications and engineering facility, officials said.

 The second hostage, Fran Crenshaw, another NASA contract worker, was found duct-taped to a chair a few hours after the standoff began. She was treated at a hospital and released.

 Police had tried to negotiate with the man but all they heard from the room was another gunshot. When they rushed in the room they found the two men dead and the woman bound at her hands and ankles.

 On a chalkboard in the room where his body was found, Phillips left a list of names and phone numbers and a scribbled note, which was not immediately understandable, The Houston Chronicle reported Saturday.

 Friday's shooting happened while the nation was mourning the 32 people shot dead by a South Korean student who killed himself after his rampage at Virginia Tech University on Monday.

 All three were electrical engineers in their early 50s who knew each other, and they may even had had lunch together earlier in the day, Johnson Space Center director Michael Coates told a news conference.

 Officials did not know the motive behind the killing.

 "Apparently there was some type of dispute between" Phillips and Beverly, Houston Police Chief Howard Hurtt told reporters.

 Phillips lived alone, was not married and had no children, officials said.

 "Up until recently he has been a good employee," Coates said.

 Coates said NASA had reviewed its security procedures, which were beefed up after the September 11, 2001 terror attacks, in the wake of Monday's massacre at Virginia Tech University but decided they did not need further tightening.

 "We never believed this could happen to our family here," Coates said.

 Visitors and employees need badges to get into the space centre, which is home to the space shuttle's mission control, and cars are randomly checked for bombs. Guns are not allowed in the complex.

 "We have a standard set of security rules that do include random vehicle searches," NASA spokeswoman Eileen Hawley said at an earlier press conference.

 "Certainly, I would believe that our security and our senior leadership is going to take a very close look at this incident, and see if there was anything that we should have done or could have done differently."

 NASA officials said mission operations were not interrupted by the incident.

 NASA chief Michael Griffin headed to the centre after the shooting, the space agency said.

 President George W. Bush was kept informed throughout the standoff, the White House said.

 "The president was deeply saddened to hear about the loss of life and he will pray for the family members and co-workers, who surely must be shocked and grieving," White House spokesman Tony Fratto told AFP.

 NASA was rocked earlier this year when an astronaut was accused of driving hundreds for kilometres (miles) to kidnap a rival for the affection of a space shuttle pilot.

 In March, Lisa Nowak, who flew on a shuttle mission last year and was fired last month, pleaded not guilty to an attempted kidnapping charge stemming from the incident.

Agence France Presse