"We're both very happy to be alive. But at the same time, the main emotion we feel is sadness, for all of those who lost their lives," Brian Clark tells PEOPLE

Stanley Praimnath was at his desk on the 81st floor of the World Trade Center’s South Tower on Sept. 11, 2001, when he saw an airplane fly past the Statue of Liberty and suddenly appear larger and larger through his office windows, until he could see a red stripe on the fuselage and the letter “U” for “United Airlines.”

When hijacked Flight 175 banked and headed straight toward him, engines roaring, Praimnath, then an assistant vice-president at Fuji Bank, dove under his metal desk, yelling, “Lord, I can’t do this! You take over!” As the nose of the plane smashed through the tower, just 130 feet from his desk, the ceiling collapsed and everything around Praimnath erupted into flames.

Curling into the fetal position, “I said, ‘Lord, I’m not ready to die — please send somebody to help me,'” he tells PEOPLE. “All I could think of was that I wanted to see my wife and my daughters again. When I saw that I was trapped, I started yelling for help.”

Thanks to a stranger named Brian Clark who heard those pleas and came to his aid instead of fleeing down the only surviving stairway in the South Tower, Praimnath became one of only four people at the impact zone to escape that morning. And he received an additional gift as well: A new best friend.

Sixteen years after 9/11, Praimnath, now 60, and Clark, 70, once an executive vice-president at Euro Brokers who is now retired, call themselves “blood brothers” — symbolically and literally.

After Clark followed Praimnath’s cries through the smoke with his flashlight and convinced him to jump over a mangled sheetrock wall so that he could help him, “he kissed me on the cheek,” Clark tells PEOPLE, “and we both dusted ourselves off and shook hands. ‘Hi, I’m Brian,’ I told him, and he said, ‘Hi, I’m Stanley. We’ll be brothers for life.’ “

Clark then took his left hand, which was bleeding from a gash, and rubbed it against Praimnath’s right hand, which was bleeding from a screw puncture wound.

“I told him, ‘I have no siblings and I’d be glad to be your blood brother,’ ” Clark recalls. “Then we rubbed our two hands together.”

“After that, Brian put his arm around my shoulder,” says Praimnath, “and he told me, ‘C’mon, buddy, let’s go home.’ “

Stanley Praimnath and Brian Clark
| Credit: Brian Clark

Today, on the 16th anniversary of the terrorist attacks, the two men will do what they have always done to observe that dark day.

“I will call Stanley and tell him, ‘It’s good to be here — it’s good to be anywhere,’ ” Clark tells PEOPLE. “We’re both very happy to be alive. But at the same time, the main emotion we feel is sadness, for all of those who lost their lives.”

“I always look forward to a call from Brian, but especially on 9/11,” adds Praimnath, who will be in Atlanta on 9/11 to speak to a community group about his experience.

“We are bonded for life because of what we went through, and he’s more than a friend,” he tells PEOPLE. “Brian is a big brother. He’s the one who remembers my children’s birthdays, my wedding anniversary, every important event. He came to my daughter’s wedding and I went to his. All of the children in my family call him Uncle Brian.”

Clark is also a snazzy dresser, rarely seen without a necktie, says Praimnath, “so I call him ‘GQ.’ And he calls me ‘Stan the Man.’ “

Credit: Brian Clark

Originally from Guyana, Praimnath felt he was living the American Dream when he arrived in New York at age 24. After he and his wife, Jennifer, settled on Long Island and raised two daughters, Praimnath worked his way up in the banking business, eventually ending up at Fuji Bank, with a beautiful view from “the top of the world” on the South Tower’s 81st floor.

Meanwhile, Clark, a Canadian ex-pat who had moved to Mahwah, N.J., with his wife, Dianne, to raise four children, was happy in his job for Euro Brokers, where he had an office on the 84th floor and had volunteered to become a fire warden after a truck bomb exploded in the World Trade Center garage in 1993.

On 9/11, after the North Tower was hit and an intercom announcement informed everyone that the South Tower was safe and there was no need to evacuate, Clark walked a distraught coworker to a restroom on the other side of the building.

At the same time, Praimnath had just arrived back at his desk after taking the elevator to the ground floor, where he and other employees were told by a security guard that they should return to their offices so they wouldn’t interfere with the evacuation of the North Tower.

It was 9:02 a.m. when Flight 175 ripped through the South Tower at a tilt, taking out most of the 78th through 84th floors. If Brian Clark had been in his office, he likely would have died upon impact like most of his coworkers. After the building swayed about six feet, he and a handful of other employees headed down Stairway A, which as it turned out, was the only stairway still intact.

Credit: Mario Tama/Getty Images

Because the stairwell was filled with smoke, the other people with Clark decided they didn’t want to risk venturing further down and felt they’d be safer if they went up toward fresh air. So they went one way, while Clark, who had heard Praimnath’s cries for help, went down.

After helping Praimnath over the wall in the darkness, the two men headed down 1,620 steps, with water gushing everywhere from broken pipes.

On the 45th floor, recalls Praimnath, “we came across a security guard who was caring for a man who had broken his back. The man couldn’t be lifted so this guy was staying with him until the end. He said, ‘Please tell my wife and baby that I love them.’ “

Praimnath pauses, then continues through tears. “These people are the unsung heroes of 9/11, not me. These are the people who said, ‘If I can’t save you, I am going to die with you.’ “

He and Clark are forever grateful that they had a different outcome. About four minutes after they stepped outside the South Tower and ran towards Trinity Church, their building collapsed, followed by the North Tower, 30 minutes later.

Credit: DOUG KANTER/AFP/Getty Images

On the first anniversary of 9/11, Clark presented Praimnath with the flashlight he’d used to find him that day. It is now on display in the 9/11 Memorial Museum, along with Praimnath’s dust-covered shoes that allowed him to run to safety.

“I know without a doubt that Brian Clark is my guardian angel,” says Praimnath, who now works for a different Japanese bank and was inspired by his experience to become an associate pastor at the Bethel Assembly of God church in Queens. “I wouldn’t be here if he hadn’t stretched out his hand that day.”

Clark feels the same way. What if he hadn’t heard Praimnath’s cries for help and had instead gone back upstairs with his colleagues?

“Why am I here? What is the reason I was saved?” he tells PEOPLE. “They’re really unanswerable questions. After going through something like we did, all you can do is try to live your best life from day to day and move forward with gratitude.”