They were among more than 30 people aboard the boat.
U.S. Customs and Border Protection officials say all but two of the passengers were from Mexico.
One is from Guatemala.
29 people survived.
“I think there's a whole lot of anecdotal evidence that suggests this will be the most lethal year in the history of the border,” said Ev Meade, a professor at the University of San Diego's Kroc School of Peace Studies.
He's been monitoring a recent rise in illegal entries into the United States.
Between 2019 and 2020, the San Diego Border Patrol sector saw 92% more apprehensions in the water alone, with 909 arrests made so far this year.