A camera focuses upon the Las Vegas Strip, where security has been ramped up due to the Oct. 1 massacre there.
LAS VEGAS — With their rifles at the ready for an active shooter, Sergeant Charles Jivapong and half a dozen other police officers moved quickly through an industrial building not far from the airport, trying to determine which victims were alive and which were too far gone to be saved.
This time, it was a drill. But Jivapong remembers when it was real: Less than three months ago he responded to reports of gunfire aimed at thousands of people at a country music concert. In just a few days, Jivapong would be out with his officers once again, this time with more than 300,000 revelers celebrating the start of 2018.
“It’s not really a matter of if it happens again, more like when,” he said. “Something like that really changes your perspective and mindset. It weighs heavily. I find myself scanning overhead all the time, thinking about what will happen if we have to do it all over.”
Las Vegas — and cities around the United States —are preparing for the first New Year’s Eve since the Oct. 1 shooting, when Stephen Paddock shot hundreds of rounds from the 32nd floor of the Mandalay Bay Resort and Casino, killing more than 50 people and wounding hundreds of others. For decades, Dec. 31 has been the biggest night of the year in Las Vegas, drawing tourists from all over the world who come to party with abandon on the Strip.
This year, officers in Las Vegas are being urged to consider the possibility of shootings from elevated positions. They are coordinating with medical personnel from the Fire Department, forming teams who will be ready to respond on the Strip and downtown if there is any kind of mass attack.
Homeland Security officials have classified the night as a top safety priority, sending snipers who will be poised on hotel rooftops, helicopters with tactical security forces, and a hostage rescue team from the Federal Bureau of Investigation. National Guard officers will also be stationed throughout the area, including at the nearby airport.
Other cities are stepping up security, as well.
In Boston, uniformed and undercover officers will be out in force in the center of the city, throughout the neighborhoods, and on subways to ensure the night is safe, according to Police Commissioner William Evans and MBTA Transit Police Chief Kenneth Green.
In addition, Evans said, some officers will be posted on rooftops to look out for threats from an elevated position. That precaution is necessary, he said, in the wake of the Las Vegas shooting in October.
“That is a new reality, unfortunately,” said Evans, who said there were no credible threats to the Boston New Years Eve gathering.
Large trucks will also be placed across streets around Copley Square, the center of First Night activities, to block “any motorist who might try to cause some harm to a crowd,” Evans said, as drivers have done in cities such as New York, London, and Nice, France.
The Las Vegas shooting has prompted the New York Police Department to reassess its New Year’s preparations as well, with the city — and Times Square in particular — long considered likely targets.
Each New Year’s Eve, the New York Police Department, and its counterparts in state and federal law enforcement, face anew the job of securing the highly symbolic spot where the ball drops, to the clamor of up to 1 million spectators packed together.
The Vegas attack has prompted police in New York to re-examine their plans. “We’re saying, ‘Let’s revisit our high-vantage security during events like this,’ ” said Stephen P. Davis, the New York Police Department’s chief spokesman.
The New York department plans to use its rooftop observation teams and counter-snipers across a broader area of real estate than in past years.
In Las Vegas, about 330,000 visitors are expected on the Strip for New Year’s Eve, according to the Las Vegas Convention and Visitors Authority, which puts on a fireworks show from seven rooftops and is billing the event as “America’s Party.”
For years, the Las Vegas Metropolitan Police Department had lobbied federal officials to give New Year’s Eve the Department of Homeland Security’s top special-event assessment rating, which would provide the city with federal officers and resources like intelligence and helicopter teams. A few weeks after the October shooting, the Police Department got word that they would receive the rating.
“We need to be able to focus on multiple shooters, on one or more above ground — we’ve got to multiply our forces,” said Chief Chris Jones, who is overseeing the department’s preparations.
Jones estimated that there would be more than 5,000 local and federal officers along the Strip. Nearly the entire length — roughly 4 miles — will be closed to traffic. Inside police headquarters, officials will closely monitor the city using hundreds of security cameras placed in the heavily trafficked tourist areas.
“We’re watching everything,” Lieutenant Dori Koren said.
Material from the Globe staff is included in this report.