The affected station is Cockrell Hill, a city in Dallas County. The story was first published by the TV station WFAA.
In a media release, the police department said: "This virus affected all Microsoft Office Suite documents, such as Word documents and Excel files.
"In addition, all body camera video, some in-car video, some in-house surveillance video, and some photographs that were stored on the server were corrupted and were lost."
The affected system displayed a pop-up demanding Bitcoins worth US$4000. After consulting the FBI's Cyber Crimes unit, the Cockrell Hill police decided that, as there were no guarantees that the encrypted files would be restored on payment of this sum, they would not yield.
"We were told by the FBI that paying doesn’t always get you your information back,” Cockrell Hill chief of police Stephen Barlag told WFAA.
"They told us that some people whose files are infected pay, and they get their files back, but sometimes it doesn't work. So we decided it was not worth it to pay, and potentially, not get anything back anyway."
The infection occurred on 12 December 2016 when one staff member clicked on a link in an email that appeared to be issued by the department.
The police media release claims that the ransomware was known as Osiris but it is common knowledge that the latest version of the well-known Locky ransomware adds an .osiris extension to the files it encrypts.
"Files that were affected did go back to 2009. However, hard copies of all documents and the vast majority of the videos and photographs are still in the possession of the police department on CD or DVD," the media release said.
"It is unknown at this time how many total digital copies of documents were lost, as it is also unknown how many videos or photographs that could have assisted newer cases will not be available, although the number of affected prosecutions should remain relatively small."