Four people were injured when a fire erupted at a mobile home in a city of Highland trailer park early Saturday morning, Cal Fire City of Highland Battalion Chief John Toon said.

At around 12:15 a.m., firefighters were dispatched to 7262 Sterling Ave. and arrived to find “heavy fire conditions,” Toon said.

Firefighters  initiated “a fast and aggressive fire attack” and kept the blaze contained, not allowing it to extend to adjacent mobile homes, authorities said.

The four patients, who suffered injuries ranging from minor to moderate, were all treated at the scene and transported to nearby hospitals, according to Toon.

Authorities did not provide information on the ages and genders of the patients, but video showed paramedics transporting at least two small children and one man onto gurneys.

The mobile home appeared to have suffered considerable damage, with its walls charred black and broken, and parts of the roof were melted.

It is unclear what started the fire.

Arson investigators were at the scene investigating the incident.

No further information was immediately available.