Investigators were interviewing people walking and biking near the Mission Valley riverbed after four suspicious fires were set within half a mile of each other. NBC 7's Dave Summers reports.
Arson investigators were called to four brush fires Wednesday that all sparked in the same vicinity, authorities confirmed.
The most recent brush fire started around 10:45 p.m. near the YMCA on Friars Road. Fire officials said a palm tree caught fire. That fire was contained to less than an acre.
Officials said another fire began around 7 p.m near the Morena Boulevard off-ramp on Interstate 8 and initially burned about a quarter of an acre.
The San Diego Fire-Rescue Department (SDFD) said officials with their Metro Arson Strike Team (MAST) were called to the scene of that fire about 20 minutes later to investigate its cause. Officials said it also began when a palm tree caught on fire and then fell to the ground, spreading the flames.
"We had fire that was almost touching the power lines. If it would have burned through, it would have caused a real emergency," Battalion Chief Ty Shimoguchi said.
Bright orange flames could be seen shooting through the brush.
The San Diego Police Department confirmed another small fire, similar in nature, happened at this same location earlier in the day, around 5 p.m.
California Highway Patrol officials shut down the westbound and eastbound Morena Boulevard off-ramps for several hours. By 8:05 p.m., the fire had been knocked out.
Meanwhile, at around 7:45 p.m., additional fire crews were called to yet another fire on the other side of I-8 and Morena Boulevard, close to Interstate 5 and Taylor Street, near Old Town San Diego.
By 8:20 p.m., that fire had been contained as well. In all, officials said it took crews about an hour and twenty minutes to tackle both fires.
Officials said fires in the Mission Valley riverbed are a persistent problem.
"We go to these quite frequently, this riverbed area with the people that live down here," Shimoguchi said.
There was a strong police presence in the riverbed Wednesday night. Everyone walking or biking in the area was asked for identification and questioned by arson investigators.
"Anyone coming out of the riverbed they just had a conversation with," Shimoguchi said. "But there are no suspects right now."
Maurice Luque of the SDFD said arson investigators had not yet confirmed if the fires were the work of an arsonist. Information on the total amount of acres burned was not immediately available.
The investigation is ongoing.