Caleb Fuller, 15, and his cousin Magon Rutledge, 17, knew they could get in trouble Friday evening for attending a party at a Hood County residence near Granbury.
That was because there were older people, and alcohol, at the gathering.
But the teens didn't hesitate to call Fuller's father, a paramedic for 20 years, for help when they saw an emaciated baby wearing socks that were so dirty they appeared to be petrified.
On Monday, Caleb Fuller's father, Paul Fuller, called the teens heroic.
"This child was saved by teenagers," Fuller said. "They stood up for what was right and being there for this child."
Eight-month-old Riley Alston was in critical condition Monday at a Fort Worth hospital, authorities said.
Riley weighed 9 pounds when he was taken to Lake Granbury Medical Center in Granbury on Friday night. A baby that age should weigh at least 18 to 22 pounds, officials said.
The child's parents, Justin and Brittany Alston, both 21, were arrested Saturday and remained in the Hood County Jail in Granbury on Monday facing charges of injury to a child and abandoning or endangering a child, Hood County Sheriff Roger Deeds said.
Bail was set at $160,000 each.
On Saturday, Child Protective Services officials took custody of two other children, an 18-month-old and a 4-year-old. The older child was placed in the custody of the child's father, and the 18-month-old is in foster care, CPS spokeswoman Marissa Gonzales said.
After the teens arrived at the Alstons' home about five miles southeast of Granbury, "my son called me and told me I need to get there quick," Paul Fuller said.
"The baby was just in a diaper. He had no fat, no muscles on him. He looked like he was 100 years old."
Paul Fuller tried to talk the parents into taking the baby for immediate medical care, he said, but they told him that they were having a party and would take their son to the hospital next week.
"I told them they had to take him now," he said. "They finally said, 'Go ahead and take him.'"
Fuller took Riley to Lake Granbury Medical Center where personnel called Hood County deputies shortly before 8:30 p.m. Riley was transferred to Cook Children's Medical Center in Fort Worth that night.
The parents were arrested after deputies interviewed them, Deeds said.
"He was in very bad shape," Deeds said. "It's a case of malnourishment."
Domingo Ramirez Jr.