SAN LEANDRO, Calif. -- San Leandro police Lt. Tom Overton said Friday that authorities have arrested two Union City teenage boys in connection with at least 16 armed robberies in San Leandro, Hayward, Castro Valley, Fremont and Union City in the past month.

Both boys formerly attended James Logan High School in Union City but have been expelled, according to Union City Police Chief Greg Stewart, who joined Overton, San Leandro Police Chief Dale Attarian and other law enforcement officials at a news conference in San Leandro.

Overton said a 15-year-old boy was arrested by Union City school resources police Officer Roberta Paul at the high school's campus on Thursday and a 16-year-old boy was arrested Friday morning prior to an unrelated court appearance at Alameda County Juvenile Court in San Leandro.

Overton also said a third suspect, 23-year-old Aaron Wysinger of Oakland, was arrested on International Boulevard near 60th Avenue in Oakland earlier Friday following a short foot chase.

He said Wysinger was arrested in connection with an outstanding arrest warrant charging a violation of his parole for a residential robbery conviction and authorities are trying to determine if he was involved in some or all of the 16 robberies tied to the two juveniles.

Overton said Wysinger is a half-brother of the 16-year-old and was arrested when authorities were looking for the 16-year-old.

Overton said authorities haven't yet determined if the Union City juveniles could be connected to other armed robberies that have taken place in recent weeks in Oakland, Berkeley and other East Bay cities.

He said the investigation is ongoing and the two teens could be connected to additional crimes.

Overton said the two boys had a well-rehearsed method of operations in which they would enter a store or restaurant together and 16-year-old would pull out a chrome or silver semi-automatic handgun and the 15-year-old would get money from the business owner and/or customers.

"They're brazen, well-rehearsed and know what they're doing," Overton said.

The first two robberies occurred in Hayward on April 12 and the two most recent robberies occurred in Union City Wednesday night, according to Overton.

All of the robberies occurred after dark, with the times ranging from 8:26 p.m. to 1:45 a.m., he said.

The incidents occurred at establishments such as QuikStops, 7-Eleven stores, Denny's Restaurants, the Manor Grill in San Leandro and a Unocal 76 gas station in Hayward, he said.

Union City Detective Howard Baron said the two boys wore hoods but didn't make an effort to hide their faces.

"They didn't seem to realize that the stores had surveillance cameras," he said.

Baron and Paul both said they've had frequent contact with the two boys and said they both have prior arrest records.

The two boys are being held at Juvenile Hall.

Overton said the case will be turned over to the Alameda County District Attorney's office and it's possible the two boys could be charged as adults.