Investigators are asking the public for help after a series of suspected arson fires in the region: two fires within an hour of each other in Antioch on Monday night, and an unrelated porch fire at a Concord home Saturday morning.

No one was injured in the blazes.

The first Antioch fire started about 9 p.m. Monday in a trash can in front of the Antioch Library at 501 W. 18th St., Contra Costa Fire Protection District investigator Vic Massenkoff said. Two males, possibly juveniles, ran from the scene and were chased for a couple of blocks by a fireman before getting away.

About an hour later, another trash-can fire broke out in the 500 block of West 20th Street, and eventually spread to and damaged a van, Massenkoff said.

The second fire was reported in the area the suspects from the previous fire were last seen, Massenkoff said.

"It's suspicious," he said.

Investigators did not identify the suspects or put out a detailed description.

Arson also is suspected in a fire set on porch at a Concord house Saturday, Massenkoff said. That fire, in the 1300 block of Joan Court, was set just before 6 a.m. and caused approximately $3,000 in damages.

Massenkoff said it originated when someone set fire to wicker furniture on the porch, but when a coffee table fell over and glass shattered, the occupants were alerted and got out of the house.

"The fire was starting to break through the front window of the kitchen, so they were fortunate to wake up," Massenkoff said. "It appears to be random. Normally in something like this it's not, but we can't find a reason why this house would've been targeted."

Anyone with information or who may have seen people in the vicinity of these fires is asked to call 925-941-3300.

Rick Hurd covers public safety. Contact him at 510-262-2728 and follow him at Twitter.com/3rdERH.