The computer systems in 23 Texas towns have been hacked and held for ransom in a widespread cyberattack across the state.

The Texas Department of Information Resources said it "is leading the response to a coordinated ransomware attack" on more than 20 Texas entities. Hackers seized control of computers Friday and remotely blocked access to important data until a ransom was paid.

Officials do not know who was behind the attacks, but they said in a press release the evidence gathered points to "one single threat actor."

Elliott Sprehe, a spokesman for the Department of Information Resources, told The New York Times on Tuesday that the attacks largely affected certain departments within the local governments but declined to specify what towns or departments were hacked.

Ransomware attacks involve a type of malware that accesses an organization's files and then locks and encrypts them until a ransom is paid to unlock them. Sprehe did not say if any of the 23 towns had paid a ransom.

Following the discovery of the attacks, Texas Gov. Greg Abbott ordered a Level 2 escalated response, just one level below the Texas Division of Emergency Management's highest alert, according to The Texas Tribune .