At the heart of the horrific shooting that killed four people at a Manhattan office building on Monday is a tragic irony: All things considered, the building at 345 Park Avenue was relatively well prepared to withstand a violent attack.

It had security personnel — a police officer and at least one security guard in the lobby. It had turnstiles that required a badge to be scanned. And many tenants of the building had the presence of mind to barricade themselves in offices once it became clear that an armed intruder had entered.

“As horrible and heartbreaking as it is that people lost lives in this, it could have been a lot worse had they not had that security protocol,” said Glen Kucera of Allied Universal, which provides security to hundreds of large companies.

He said that additional security might have stopped the attacker but that it was very difficult to completely neutralize an armed assailant who had “made up his mind to hurt people” and was willing or even determined to die. The gunman double-parked his car near the building and began firing upon entering. He killed four people before turning the gun on himself.

Experts on building security say most large office buildings in New York City have something resembling the security measures at the Park Avenue building. They said the real question wasn’t so much whether New York buildings would take additional steps in the aftermath of Monday’s tragedy, but whether buildings and employers in other cities might revise their approaches to be more like those in Manhattan.

“New York is the one city in America where, by far, virtually all high-end buildings have turnstiles,” said Mark Ein, the executive chairman of Kastle Systems, a building security firm with clients around the country. That is not the case in most cities, he said.