Crews battle structure fire at Los Rios Rancho in Oak Glen

OAK GLEN, Calif. (KABC) -- Firefighters were working to extinguish a blaze at Los Rios Rancho in Oak Glen on Friday morning.

The four-alarm fire broke out just after 2 a.m., according to Cal Fire.

Multiple structures were involved, fire officials said.

RELATED: 2 separate fires in LA damage housing complex for veterans, dry cleaner and historic theater

Raging flames and thick smoke reached into the morning sky across parts of Los Angeles Wednesday as firefighters battled two massive structure fires.

The extent of damages is not yet clear.

The cause of the fire is under investigation.

DEVELOPING: This report will be updated.