Houston firefighters shut down a portion of the street and used a fire hose to create a makeshift water park for the complex's children.
As HFD's Engine 9 was responding to a call with lights and sirens, it was hit by the light rail train, HFD officials said.
An official with the Houston Fire Department said that firefighters did not hear any fire alarms or see any sprinklers activated.
Six families have been displaced after a building was lost in the apartment complex fire, HFD officials said, adding that no civilians were injured, while one firefighter was treated for an ankle injury.
A new study by the International Association of Firefighters claims the Houston department needs tens of millions of taxpayer dollars to ensure people in emergencies can get the help they need.