OKLAHOMA CITY — Oklahoma’s state computer network was unsuccessfully targeted by Russian hackers ahead of the 2016 general election, state election officials confirmed Friday.

U.S. Department of Homeland Security officials told state election officials that Russian hackers conducted a common form of surveillance scan looking for any vulnerability in the state’s computer network, said Oklahoma Election Board spokesman Bryan Dean.

“No vulnerabilities were found, no penetration was made into any system, and no further activity occurred,” Dean said. “The scan targeted a state computer network, not the election board network, and the really important thing to note is that these types of scans are incredibly common.

Oklahoma is one of 21 states that Homeland Security said were targeted by Russian hackers.

Unlike some states, where data such as voter registration statistics are maintained separately by counties, Oklahoma’s voter data is centrally maintained by the state’s information technology department under the Office of Management and Enterprise Services.

“Our voter registration system is secured by the state,” Dean said. “The fact that we have the system we have provides us with an added layer of security.”

Dean says state election officials have discussed with Homeland Security and with state technology experts ways to make the state’s system even more secure.