BRENTWOOD (CBS SF) – Two early morning car fires in Contra Costa County Thursday are the latest in a string of suspicious East Bay car fires this week, and appear to be related to other fires this year.

Fire investigators said they deemed the two Brentwood car fires as suspicious, saying it was highly unlikely two cars would catch fire around the same time in the same neighborhood.

READ MORE: Mothers Tearfully Remember Children Slain In Bay Area Homicides

The fires bring the number of suspicious possible car arson cases in the East Bay to five in just the past week.

Thursday afternoon, Contra Costa Fire Protection District said in a Facebook post “In looking at recent fire activity, we can tie fires back to earlier in the year. The exact number of fires is unknown.”

In one of Thursday’s incidents, a neighbor’s cell phone video captured the intense flames ripping through a Honda parked in front of the Brentwood home on Highland Way. Firefighters said they received the call about the fire at about 3:38 a.m.

Video then shows firefighters arriving at the scene in time to stop the fire from spreading into the house.

“The whole front of the car engulfed in flames,” said neighbor Chris White.

Shortly before that fire at around 3:30 a.m. less than a mile away at 1156 Hollowbrook Court, a truck went up in flames.

A neighbor recorded video after hearing several explosions across the street.

The truck owner who gave his name as John said his family was fast asleep in the back of the house when a neighbor alerted them.

READ MORE: Oakland Ties 2020 Homicide Total in First 9 Months of 2021

“So our neighbor was leaving for work. He rang our door bell continuously,” said John. “So we quickly rounded everybody up and ensured the fire department was on its way.”

Fire firefighters put out both fires before any one was hurt. Investigators believe the cause could be arson.

The Brentwood fires follow a string of three other car fires that happened this week in Walnut Creek, Lafayette and Martinez.

The incidents have sparked concern among Contra Costa County residents.

“It happened in front of my house. It makes me worried and scared,” said neighbor Rochelle Soriano. “Who are they targeting? Why are they targeting certain cars or families? I don’t know.”

The homeowners at Hollowbrook Court were left with charred pieces of metal, a destroyed garage door and many unanswered questions.

“Just frustrated. There’s no reason for this stuff to happen,” said John. “It’s putting people’s lives at risk for no reason.”

The Contra Costa County Fire Protection District asked the public for help on its Facebook page. “If you live in an area where there has been a recent car fire, and you have any information that may be of use, such as camera footage, noticing strange vehicles or people in the area, or anything that is out of the ordinary, please contact us through the Arson Tip Line at 1-866-50-ARSON.”

MORE NEWS: Advocates for Immigrant Rights March From Santa Rosa to Healdsburg