The overnight tryst began in Baltimore, with three men, two dressed as women. It continued at a motel on U.S. 1, and when one of the men woke up on Monday morning, his two cross-dressing companions, and his Ford Escape, were gone.

The dark-colored Escape was headed south on the Baltimore-Washington Parkway. Its driver, in what authorities believe could have been a mistake, took a restricted exit leading to a security post at the sprawling campus of the National Security Agency at Fort Meade, Md.

An NSA statement said the driver ignored police commands to stop and instead accelerated toward a police vehicle as at least one officer opened fire. The stolen SUV crashed into the cruiser. One man died at the scene, and the other was rushed to a hospital for treatment. An NSA officer also was injured, though officials did not say how.

What had first appeared to be an attempt to breach security at the listening post that eavesdrops on communications throughout the world now appears to be a wrong turn by two men who police believe had robbed their companion of his vehicle and perhaps didn't stop because there were drugs inside.

A spokeswoman for the Baltimore office of the FBI, Amy Thoreson, said early in the investigation that authorities "do not believe [the incident] is related to terrorism." A law enforcement official said: "This was not a deliberate attempt to breach the security of NSA. This was not a planned attack."

Police have not released the identities of the people involved, or the conditions of the man who survived the incident and the injured NSA officer. The NSA statement did not say whether either person in the car was struck by gunfire or was injured as a result of the crash.

Details about how the incident began were pieced together with information from law enforcement officials and others familiar with the case, who spoke on the condition that they not be named in order to discuss a pending case.

A Howard County police spokeswoman confirmed that the men involved stayed at a Jessup motel and that the owner of the SUV called police on Monday morning to report it stolen.

Police officials said late Monday afternoon that they were still trying to piece together the sequence of events and locations. One official said it appears that the owner of the SUV picked up the other two men in Baltimore, though the official said detectives had not confirmed that account entirely.

The officials do know that the three men checked into the motel room and stayed the night. One official familiar with the investigation described the episode as "prostitution and drug-related."

Mary Phelan, a spokeswoman for the Howard County Police Department, confirmed that the SUV stolen from the motel was the vehicle that ended up at the NSA checkpoint.

Officials said they were trying to sort through the vehicle owner's statement; it was unclear whether the person injured in the incident could be interviewed at the hospital.

The encounter at the NSA occurred shortly before 9 a.m., when the vehicle entered the NSA complex in Anne Arundel County, Md., and "failed to obey an NSA police officer's routine instructions for safely exiting the secure campus."

One official said the vehicle struck a security officer and the security barrier. The NSA statement said the "vehicle accelerated toward an NSA police vehicle blocking the road" and that police "fired at the vehicle." It then crashed into the police vehicle.