The discovery came shortly before 8:00 p.m. Thursday near the banks of the creek.
Police and family members confirmed later that the body was in fact that of the 18-year-old Krewson.
Krewson and 18-year-old Dan Tadrzynski both disappeared while swimming in the creek Tuesday night.
Tadrzynski's body was located late Thursday morning just off East Bristol Avenue in Feasterville, Bucks County. Authorities say it was Perry Krewson's uncle who found Tadrzynski.
Parents Perry and Lisa Krewson joined Dave and Ann Tadrzynski thanking all of the first responders, crews, and volunteers who helped searched for their sons.
Krewson's father said, "Police, fire... Perry was enlisted in the Marines. He was getting ready to leave. The pulleys, which are the young fellas that haven't left yet ? there were probably 40 to 50 of them walking the banks all day today. And I can't thank them all enough."
Tadrzynski and Krewson graduated high school this year and Krewson was supposed to start Marine boot camp in one month.
The discovery of Tadrzynski's body came more than 36 hours after the two teens disappeared while swimming in the creek at about 10:30 p.m. Tuesday near the Neshaminy Falls train station.
Police say a cell phone belonging to Tadrzynski was in a waterproof case and emitting a signal from the area of the Neshaminy Creek near Newportville Road. So that's where a police marine unit was searching Thursday morning.
Meantime, the young men's family members and friends were conducting their own searches, including Krewson's Uncle Walt, who was about four miles upstream from the police in a kayak.
"A couple of people went out in kayaks on their own and concentrated on the upper end. He was in the middle of the creek and they saw something protruding and then called 911," said Director of Public Safety Fred Harran.
In the middle of the creek, behind the Neshaminy Animal Hospital, they found Tadrzynski's body.
Police had searched that area earlier. But by Thursday morning the water had receded.
"That whole area was submerged. The water was actually much higher. I was looking at the water marks today. That water was a lot higher than it is today. He would have been totally submerged," said Harran.
In light of the discovery, boats and planes were re-deployed to search the creek again Thursday afternoon.
"The other boy probably was submerged and is either still submerged. . . he might not even be in this location. He could be a lot farther down," said Harran.
Meantime, the young mens' families, who are friends, are leaning on each other for support.
"I couldn't imagine what they're going through. I don't think anybody could imagine it. Nobody could say, 'I know what you're going through' unless you've been through it," Harran said.
"It's awful, it's such a tragedy. I feel so bad for the family," said Elizabeth Wenzel of Bensalem.
"It's tragic what happened," said Tom Badman of Bensalem.
Police said they are not stopping family members from searching the creek on their own, but they are urging caution. Areas of the creek can be up to 10 feet deep and they don't want anyone else to drown.