The Maine Secretary of State’s Office said Wednesday it is investigating a potential security breach in the computer system that contains records on Maine’s registered voters.

The state was notified Wednesday afternoon by the cybersecurity monitoring arm of the U.S. Department of Homeland Security that Maine’s Central Voter Registration system had been compromised. The breach was detected as part of a regular security check.

Maine Secretary of State Charlie Summers said a computer in an undisclosed town office apparently had been infected by malicious software — commonly known as malware — that may have then infected the centralized data system.

“I am in the process of assessing what, if any, information has been compromised,” Summers said in a statement released Wednesday afternoon. “I have taken immediate action to shut this computer down and disable the username and password assigned to the town clerk.”

The Central Voter Registration system, or CVR, contains personal information on registered voters including names, addresses, dates of birth and, in some cases, driver’s license numbers. The system does not contain Social Security numbers, Summers said in an interview Wednesday.

Summers declined to name the town office where the breach appears to have originated until his office more thoroughly understands the extent of the situation and whether other towns’ computers also were compromised. He said his office hoped to have more information late Wednesday or early Thursday.

Summers said they strongly suspect that some information was accessed, however.

“We just don’t know how much or the size” of the breach, he said.