A Sound CU representative said Watermark CU's risk management department was notified of a skimming breach by BECU. Sound CU determined someone had been placing a device on the vestibule door of a branch ATM and leaving it there for a few hours a day for approximately three weeks.

A total of 230 payment cards were involved, 68 of which did not belong to Watermark CU members; following the breach, Sound CU contacted each affected member and notified the institutions of the non-members, the CU said.

Buzbuchi and Eleckes appeared to have skimmed account information in Washington, Idaho and Arizona, sometimes by installing skimming devices on the access doors of lobbies where ATMs are located, the U.S. Attorney's Office said.

G-Sallassie is charged with stealing more than $394,000 after skimming information from as many as 1,800 accounts in Washington, Oregon, California and Nevada, according to the U.S. Attorney's Office. Seattle police arrested G-Sallassie at a Chase Bank branch in South Seattle after Chase security personnel caught the suspect attempting a fraudulent ATM withdrawal.

BECU said approximately 280 member accounts were compromised in the attacks.

“BECU was one of the multiple financial institutions targeted by the individuals recently arrested and the BECU security risk team played a critical role in ensuring the individuals were apprehended,” the credit union said. “Since this event, BECU has implemented additional ATM security controls designed to deter future skimming incidents.”

First Tech FCU confirmed that some of its members were affected by the skimming scam and said it notified members and activated its incident response plan immediately.

“We did cooperate fully with the authorities investigating this scam and would like to thank them for their diligence in making the arrests,” First Tech CU said. “We continually educate our members about how to protect themselves from fraudulent activities.”

Two more arrests were made last week in connection to the skimming scam. Ismail Sali of Kirkland, Wash. and Eugen Tirca, also residing in Kirkland, Wash. and a Romanian national illegally living in the U.S., are charged with possession of access device equipment, the U.S. Attorney's Office said. Investigators believe the suspects are connected to defendants who were previously arrested and prosecuted for skimming.

“We believe that with this most recent arrest, we have located and dismantled the nerve center of one of the most prolific rings, which used illegal immigrants from Romania to commit the frauds,” said U.S. Attorney Jenny A. Durkan, chair of the Justice Department's Cybercrime and Intellectual Property Enforcement working group.

According to a complaint filed by the U.S. Attorney's Office, Sali and Tirca allegedly stole account information by installing electronic skimming and video surveillance devices on Seattle area ATMs. Their crimes affected account holders at BECU, the $4.4 billion, Anchorage-based Alaska USA FCU and several large banks, the complaint said.

Alaska USA FCU said it could not comment on any investigations in process.

The U.S. Secret Service Electronic Crimes Task Force is investigating the recent skimming incidents. The arrests come on the heels of an ATM skimming gang leader's July sentencing and the June accusation against four Romanians in an ATM skimming scam in New York.