Vanessa Villa went into labor outside Engine 14 in the 1100-block of West Chicago Avenue around 8:50 a.m.
WATCH: Fire captain describes how she helped deliver baby outside station
Villa was being driven to the hospital by a friend who pulled over at the fire house as the mother's contractions were only about a minute apart.
"She knew it was happening and that it was not going to wait," Capt. Barbara Ohse said. "It was imminent."
Led by Capt. Ohse, the firehouse jumped into action.
"It went from no baby to 'we are having a baby!'" firefighter and EMT Aidan Flahaven said.
Friday night they all formally met for the first time. Firefighters gave the baby a new onesie, and gave Villa's other child a shirt.
The baby was named Julian Lopezi.