Police guard the approach to a parking lot behind the Luxor hotel-casino in Las Vegas today after a man who police say was an employee was killed in an explosion. Another person escaped injury. ISAAC BREKKEN | Associated Press   Officials investigate the scene of an explosion on the top floor of a parking lot behind the Luxor. Police said the blast was not a terrorist act, but the apparent murder of a hotel employee. ISAAC BREKKEN | Associated Press

A woman who left the Luxor hotel-casino with the victim and was standing nearby escaped injury when the device blew up just after 4 a.m. on the top level of a two-story parking garage, police and federal Bureau of Alcohol, Tobacco, Firearms and Explosives agents said.

Police did not immediately identify the dead man or the uninjured woman.

"She is very lucky she wasn't killed or extremely injured," Tom Mangan, a senior special agent with the ATF office in Phoenix, said of the witness.

"She did not have a scratch on her," said Officer Bill Cassell, a Las Vegas police spokesman

Cassell said detectives believed the man was the intended target of the device and characterized the slaying as "a homicide with an unusual weapon."

Mangan called the bomb "a homemade device, an improvised explosive device, or an IED" that produced a blast about the size of a stick of dynamite and blew a 12-inch hole in the man's car.

Shrapnel penetrated nearby vehicles, and pieces of the bomb were scattered across the parking structure, Mangan said. He declined to describe the bomb's components or confirm a broadcast report that the bomb had been disguised as a cup.

Deputy Las Vegas Police Chief Ted Moody called it "a small device that was constructed in such a way to target a single individual victim."

"It was successful in doing that, unfortunately," Moody said.

The man was taken to University Medical Center in Las Vegas, where he was pronounced dead, the Clark County coroner's office said.

Police said the blast was not a terrorist act or a mob hit, but an apparent murder of a man who worked at a business inside the Luxor. Police would not say why the man might have been targeted.

Mangan confirmed reports by various Luxor employees that the man worked at a Nathan's Famous hot dog stand.

Workers at Nathan's would not comment, and messages left after business hours at Nathan's corporate offices in Westbury, N.Y., were not immediately returned.

The eatery is one of a handful of non-casino businesses that remain open all night in a second-floor food court near an arcade and several shops inside the Luxor, a pyramid-shaped hotel with more than 4,400 rooms and 4,200 employees at the south end of the Las Vegas Strip.

Homicide investigators spent the day reviewing casino and parking lot security videotapes, hoping they would show who left the device atop the man's car.

Moody said investigators were reviewing videotapes from multiple cameras in and around the two-story parking structure.

Access to the garage remained restricted through the day, frustrating hotel guests who could not retrieve their vehicles. It was reopened late Monday.

"They said they'd call me and let me know when," said Shon Brown, 32, a real estate agent from Lakewood, Calif., who wheeled his luggage away from an exit overlooking a sun-splashed pool and walked back into the casino. "But my phone's in my car."

Gordon Absher, a spokesman for MGM Mirage Inc., which owns the Luxor, said vehicle owners were allowed to remove their vehicles from some parts of the parking structure after they were inspected by authorities.

ATF Special Agent Nina Delgadillo, regional spokeswoman for the agency in San Francisco, said the painstaking evidence collection process was important at a crime scene that will revert to a busy parking lot once authorities leave.

"You don't want to miss any bits of evidence that might provide investigative leads," she said.

Absher said the Luxor was not damaged and operations continued normally, except on the top floor of the parking garage.

Several hours after the explosion, a report of an unattended bag prompted a brief evacuation of the race and sports betting area inside the casino. Police were called about 11 a.m. and a bomb squad determined the bag was an empty computer case, a police spokesman said.

Absher said there was no connection between the incidents other than "awareness was heightened" among employees.