As tourists and employees scattered, Lampert dropped his hot dog and hunkered down.

Moving slowly amid the stampede, one man in a cream-colored trench coat walked by clutching a gun in his hand. Lampert said he made eye contact with the man as a magazine dropped out of the Springfield XD 9mm semiautomatic handgun.

The man said, "I'm going to (expletive) kill you," Lampert recalled.

Drawing on military training and some liquid courage, the 24-year-old university student and North Dakota National Guard staff sergeant jumped to his feet and grabbed the man.

The gun fell to the ground and Lampert put him in a choke hold. Soon three more men ran over to help subdue the gunman until security and police arrived.

Four people had been shot by Steven Francis Zegrean, Las Vegas police said. And he had a lot more ammunition.

On Friday, Lampert, who was in town to attend the bachelor party of a buddy for whom he'll be the best man, was hailed as a hero.

The Iraq war veteran said he did only what anyone else would have done. "I'm not a hero," he said.

So why did he do it?

"I was drunk," he said.

Las Vegas police detectives were trying on Friday to determine what led Zegrean to snap.

Police know Zegrean was emotionally distraught when he entered the hotel about 12:43 a.m. from the overpass that crosses Las Vegas Boulevard South from the MGM Grand.

Police said he might have recently lost a job. Financial troubles or relationship problems might have influenced him or maybe a combination of the three, police said.

"I was trying to create a conflict," the 51-year-old told investigators during an interview, a police source said.

He might have been attempting to commit suicide by cop, where a person forces officers to kill him, police said.

But he was stopped by four men. All of them unarmed. All of them on vacation.

Lampert, a zoology major and criminal justice minor at North Dakota State University at Fargo, was the first to reach Zegrean, police said.

He was joined by three others: David James, a Navy Reservist from Jacksonville, Fla., and brothers Robert and Paul Ura, both special agents with the Florida Department of Law Enforcement.

"These men are heroes," said Capt. James Dillon of the Police Department's robbery/homicide unit. "The subject was capable and he was motivated to continue shooting his weapon, but he was tackled and then taken into custody after the first volley of rounds."

Zegrean was booked into the Clark County Detention Center on four counts each of attempted murder, battery with a deadly weapon, conspiracy to commit murder, 16 counts of discharging a firearm into an occupied structure and burglary with a deadly weapon. Dillon said the burglary charge can be applied to a person who enters a structure with the intent to commit a crime.

Zegrean was on suicide watch and being held without bond.

None of those wounded in the incident received life-threatening injuries. A woman and a teenage boy were wounded; a man was grazed by a bullet; a woman was hit by a bullet fragment or shrapnel; and a woman was bruised and scraped when she fell amid the crowd of people exiting the casino, police said.

Zegrean's mug shot shows dried blood between his eyes, on his mouth and right ear. Dillon did not know how Zegrean received his injuries, but said he might have gotten cut when he was taken down by the four men.

Police tried Friday to trace Zegrean's movements in the days before the shooting.

On Wednesday, somebody called police and told them Zegrean was suicidal. Police and paramedics arrived at his Las Vegas residence and spoke with him, police said.

"But there was no apparent injuries, and the information he provided and his demeanor and actions at the time led the officers and medical personnel to believe that he was not a threat," Dillon said.

Police then left Zegrean's home. At some point investigators believe he put on the trench coat, armed himself with the handgun and spent the next 24 to 36 hours walking up and down the Strip in the sweltering heat apparently seeking to engage a member of law enforcement in a confrontation.

"He did not have the encounter we believe he was hoping to have with law enforcement. We don't know why he picked the New York-New York. At this time we think that this was a random act," Dillon said.

According to surveillance video, Zegrean was walking around inside New York-New York 20 minutes prior to the shooting, Dillon said.

Melody Zegrean, 43, a Las Vegas resident who identified herself as Steven Zegrean's cousin, said he had been divorced for several years and estranged from most of his family since his ex-wife remarried.

"I love my cousin and everything," she said, "but his temper and not being able to relate has really gotten worse recently. He's been threatening the family for some time now. He's been pushing everyone away."

She described Steven Zegrean as a Hungarian immigrant and unemployed house painter who liked to gamble.

In 2002, Zegrean and his wife filed for divorce to end their 20-year marriage, according to court records. Mary Zegrean got sole custody of their two teenage children, and the couple sold their home and split the proceeds.

Six months later, in March 2003, Steven Zegrean married Beatrix A. Horvath. But he filed for an annulment two months later, saying Horvath only married him for immigration reasons and never intended to live with him.

Mary Zegrean remarried in June 2004.

She filed a report with Henderson police in January against her husband for making annoying phone calls, officer Todd Rasmussen said. That case remained open.

Gordon Absher, spokesman for MGM/Mirage, which owns and operates New York-New York, said business was going on as usual by 7 a.m. Friday.

"There have been a lot of questions," from guests, Absher said. Casino officials have tried to quell fears by talking up the hotel's surveillance system, security personnel and relationship with police.

When officials do that, "people revert to their normal satisfaction that Las Vegas is a very safe and very secure destination," Absher said.

On the pedestrian walkway outside the hotel Friday morning, Klaus Torp, Magnus Lind and two fellow Norwegians posed for photos to commemorate their trip. But Torp, 28, and Lind, 31, will return home with more than the usual tourist snapshots: They'll also carry memories of running for their lives after the gunfire started.

Lind was waiting in line to buy a slice of pizza when he heard a series of booms and saw people running his way.

"It was total chaos, and I started running too," Lind said.

Torp had just come down the escalators from the mezzanine when he heard gunshots behind him. At first he thought they were firecrackers. Then he saw an employee run past him screaming about a shooting.

"Everybody dived under the poker tables," he said. "Everybody was under tables or on the floor."

Soon security guards and police armed with shotguns appeared. Some tried to calm the panicked crowds, Lind said.

Torp said he and Lind had nightmares that morning, but they weren't going to let it ruin their vacation.

"It can happen anywhere," Torp said.

Absher praised the four men who subdued Zegrean.

"We're very appreciative of the brave actions they took, stepping in to prevent this incident from becoming any more tragic," Absher said.

MGM/Mirage acknowledged that the incident might have put a damper on the four men's vacation, Absher said.

"We are making sure they are having an enjoyable stay. This is probably not how they planned on spending the weekend," he said, adding that they will be offered free rooms on a return trip.

Review-Journal writers Brian Haynes and Paul Harrism and The Associated Press contributed to this report.