The blaze broke out just after 1 p.m. near the area of Lake Avenue and Loma Alta Drive.
It's being called the "Cobb Fire" because it's close to the Cobb Estate.
The Los Angeles County Fire Department, and the Angeles National Forest Fire Department are tackling the flames.
|New Incident| We have responded to a new fire with assistance from @LACoFDPIO near Cobb Estate above Pasadena. The fire is 3-5 acres heading towards the Sam Merrill and Sunset Ridge trails. We will be in unified command with @LACOFD. pic.twitter.com/rwxJOr5bUK— Angeles National Forest (@Angeles_NF) February 20, 2022
The fire has burned three to five acres, and is heading towards the Sam Merrill and Sunset Ridge trails, according to officials.
No injuries have been reported, and no structures or homes are threatened.
The fire is 10 percent contained. The cause is under investigation.