They quickly realized that what they were looking at was a person, an elderly woman, floating face down as the current swept her away.
"Donnie jumped from the vessel (and) brought her up out of the water," Cajun Navy volunteer Joshua Lincoln told CNN's John Berman on "AC 360" Monday night.
"Ricky was manning the boat. He jumped in immediately also. I was at the front of the boat, leaving us in a serious current with nobody manning the motor in the back," Lincoln said, referring to his colleagues by their first names only. The New Orleans Times-Picayune identified them as Donnie Davenport and Ricky Berrigan.
"So they quickly grabbed her, started to resuscitate her, and were able to get her to breathing slowly, and then we were able to control the boat. We got her back to safety, and that's that."
The rescue of the Houston woman on Monday was one of several credited to volunteers from the Cajun Navy, a grassroots citizens' organization that came together in the aftermath of another hurricane in another state more than a decade ago.
In the devastation and deep water left by Hurricane Katrina, Louisianans took to their boats to help each other, and the Cajun Navy was born. Now, they are helping their Texas neighbors.
A flotilla of some 20 boats, hauled on trucks and trailers, came to Houston over the weekend to join the rescue effort, according to Cajun Navy organizer Clyde Cain.
"We started deploying people (Monday) morning at 3 a.m.," Cain told CNN. "Our goal is to help people get out if they are trapped in their homes or apartments, get them to safety."
Later Monday, Cain told CNN's Chris Cuomo that more boats had come from Louisiana after the initial group.
"We have no idea how long it's going to last (in Houston)," he said.
The Cajun Navy has grown since it was organized in Louisiana in 2005 and now has thousands of followers on its Facebook page. The organization helps communities with storm preparations, rescues and food distribution. It has no official relationship with the US Navy.
Facebook and the phone application Zello is how the group finds out about people in need and connects them with volunteers who can assist them, Cain said.
And with Harvey, now a drenching tropical storm, heading toward Louisiana,
there is the looming possibility the Cajun Navy might be needed back in its home state.
Lincoln explained their presence in Houston in personal terms of getting help, then giving it in return.
"In my life I've been through a lot of storms including Katrina," he said. "Seeing how people in Texas responded and helped us in a disaster kind of tugged at my heart. My house was flooded and I lost all kinds of things during Katrina."
When he heard about the disastrous situation in Houston and the people desperate for aid and assistance, he decided, "I'm not going to work. I'm just going to head that way and meet up with somebody and do what I can do. That's what every man in the Cajun Navy has done, (every) man and woman."
Lincoln said the elderly woman pulled from Houston's waters was "doing fine" Monday night and was reunited with relatives.
"We found three family members -- the family members thought she was safe at a high ground, (at) a school. They were misinformed. A gentleman through the Cajun Navy in Baton Rouge was able to locate the relatives and have them get back over to her."