The New York Police Department officers didn't know what was going on, but they knew they needed to help. They raced toward the blast.
"The flash was really fast and then just a lot of smoke," Sendrowski, 34, said. "When we got to the corner there was a lot of people kind of just waving their arms and just kind of pointing down the block."
They saw a mangled dumpster flung across 23rd Street and later learned it was launched by a device made of shrapnel and pressure-cooker bombs. Officials would eventually call the explosion an "act of terror."
Amid scorched trees, shattered glass and worries there could be more explosives in its wake, both officers quickly urged bystanders to leave the area.
"I can't imagine even what they thought of. We saw it too but they were at ground zero, they were right there," Campanella, 25, said.
The blast in New York's Chelsea neighborhood injured 29 people
on September 17. But in the moment, Campanella said they didn't know whether people had been killed.
"I just saw blood on their clothes. They were just hysterical. I tried to calm them down and say help is on the way, and that was pretty much all I could do," he said.
At that point, the two men began breathing in smoke from the explosion. Campanella turned to Sendrowski, telling him to hang back. "We didn't know what kind of chemical agents we were dealing with," Campanella said.
The officers roped off the area as their fears were confirmed. State troopers found another unexploded device just a few blocks away, made of the same deadly materials.
Both officers quickly alerted their families.
For Campanella, that was his dad. Someone who would understand.
"My father, my role model, he was a cop," said Campanella, who has been an NYPD officer for four years. "I called him up and I said, 'Hey, listen, there was an explosion, I'm okay. I'm safe.' That was pretty much it. Because he knew that it's probably an active investigation, an active scene, and he didn't want to take a lot of my time."
The officers worked through the night, answering calls to the 10th Precinct over suspicious packages.
Over the next 48 hours, investigators followed leads linking the two pipe bombs to Ahmad Khan Rahimi. The suspected terrorist was captured that Monday morning after a New Jersey bar owner alerted police about a man sleeping in the doorway of his bar. A shootout ensued and Rahimi was arrested.
Rahimi has since been moved from a hospital to the New Jersey State Prison in Trenton. He has pleaded not guilty to various state charges, including attempted murder.
"I was happy to see him arrested. I didn't know what else he had planned. I have a lot of friends and family in the city," said Sendrowski, who has been an NYPD officer for nine years.
But even with the accused bomber off the street, the officers felt the impact of an attack on New York.
"You almost want to take it personal because this is your city," Campanella said. "You don't know if he had planned for more targets."
"It was a sigh of relief," Sendrowski said, "that he's not out there committing more acts like that."