SAN DIEGO (FOX 5/KUSI) -- Fire crews responded to a series of separate brush fires in Mission Valley Tuesday afternoon. According to San Diego Fire-Rescue, both fires were in the area of 2400 Murphy Canyon and Rancho Mission roads at Camino del Rio N. A fire started in the riverbed shortly after crews stopped a separate brush fire that was reported around 12:30 p.m. at the dead end of Murphy Canyon Road, authorities said. The initial fire burned about a 50' by 50' area of brush, according to authorities. No structures were threatened or damaged, and no injuries were reported. This is a developing story. Check back for updates.