MODESTO (CBS13) — Firefighters say an early morning fire at a pallet yard went to four-alarms on Friday.

The scene is along the 1700 block of Reliance Street in Modesto.

READ MORE: Yastrzemski's Bat, Glove Help Giants Hold Off Tigers 4-3

The fire was still smoldering through the morning hours.

Modesto Fire says the incident, which started just before 3:30 a.m., prompted a four-alarm response. Firefighters from Modesto, Ceres, Turlock and the Stanislaus Consolidated Fire Protection District responded.

READ MORE: Garbage Truck Driver Discovers Body When Depositing Trash At Yolo County Dump

Firefighters were able to contain the flames to the yard, officials say.

Exactly what started the fire is now under investigation.

MORE NEWS: Animal Shelters See Rise of Returned Pets, Citing Affordability Concerns

Crews remain at the scene through the early morning hours as the fire smolders.