SAN DIEGO -- Firefighters worked to put out two brush fires which broke out near homeless camps Thursday.

The first fire burned about an acre and a half of brush in the San Diego River bed near Old Town, but no injuries were reported, officials said.

Witnesses reported seeing fire and smoke coming from the riverbed by westbound Interstate 8 on the Morena Boulevard offramp around 2:20 p.m., said a San Diego Fire-Rescue dispatcher.

Firefighters had difficulties reaching the flames due to the river bed's terrain but were able to put the fire out about 40 minutes later, the dispatcher said. No one was injured during the fire. The cause of the fire is under investigation.

The second fire broke out around 4 p.m. Thursday afternoon at 904 33rd street, near E street.

People driving on the 94 could see flames and plumes of smoke coming from the freeway.

The fire was not considered a big threat to homes, but it did disrupt one family's Thanksgiving meal.

Firefighters tell 10news there is a homeless camp near the area where the fire broke out. It took them about 15 minutes to knock the fire out. No injuries were reported, and an investigation into the cause is ongoing.