RICHMOND -- Police arrested four boys, the youngest 12 years old, after officials said they robbed a man at gunpoint about two blocks from the Richmond BART station early Friday.

The arrests come on the heels of months of increased robberies in the neighborhood blocks surrounding the transit hub, which police believe child bandits have targeted as an easy spot for sidewalk stickups to get cash, jewelry and cellphones. Eight juveniles have been arrested on suspicion of committing robberies in the area in the past month, and robberies in the 1,500-foot radius around the BART station are up more than 30 percent this year.

"We're seeing a very cavalier approach from some juveniles in the area," police Capt. Mark Gagan said. "They think it's a game. It's disturbing."

At 2:20 a.m. Friday, two boys in dark hooded sweatshirts approached a 20-year-old man as he walked near 17th Street and Roosevelt Avenue.

"One of the suspects produced a pistol and demanded personal items," Gagan said. "The victim handed over his cash and his cellphone."

An officer responded to the scene minutes later. The victim said the teens linked up with two others nearby and continued walking, Gagan said.

A short time later, officers spotted two boys in the 600 block of Barrett Avenue. The boys fled, but police arrested them at 17th Street and Pennsylvania Avenue after a short pursuit, Gagan said. The other two were arrested nearby minutes later.

Gagan said "a weapon was recovered nearby" but declined to give further details, citing the ongoing investigation.

In addition to the 12-year-old, others arrested were two 14-year-olds and a 16-year-old. The 12-year-old was released to his guardian, and the teens are in juvenile hall, Gagan said.

"We believe (these boys) are responsible for many other robberies in the area, but descriptions in some of the other robberies don't match," Gagan said. "We think there are other juveniles or young men still out there committing robberies."

The increase in robberies around the BART station became apparent April 15, when police identified a trend of youthful-looking suspects committing armed robberies near the station.

Four other youths, three age 15 and one age 16, were arrested on suspicion of committing robberies on April 12 and April 15, bringing the total number of juveniles arrested on suspicion of committing robberies near the BART station to eight in the past month.

On the BART station property itself, which is within the jurisdiction of BART police, there was a slight increase in robberies and property crimes in 2012, but crime is down overall so far in 2013, according to BART police Deputy Chief Ben Fairow.

In March, a man was shot and killed near the entrance of the station in afternoon daylight in front of dozens of commuters.

"We take safety in our system very seriously," Fairow said. "We have increased patrols (at Richmond BART), and that will continue."

Contact Robert Rogers at 510-262-2726 or rrogers@bayareanewsgroup.com. Follow him at Twitter.com/roberthrogers.