CHULA VISTA (CNS) - A fire broke out early Thursday in a riverbed in Chula Vista.
   
The blaze blackened an area of unknown size in the vicinity of Fourth Avenue and Beyer Way. The rugged terrain hampered firefighters' efforts, according to broadcast news reports.
   
Fire crews used about 2,000 feet of hoseline, but still had a hard time reaching the blaze, officials said.

The cause of the fire was not immediately known.