The personal data of 848 current and former John Hopkins University students were stolen,  The Associated Press reported.

The names, email addresses and telephone numbers of the school's biomedical engineering students were posted online  Thursday after they were stolen by someone claiming to be part of the hacker group known as anonymous.

 "The breach apparently occurred late last year, but came to light when someone posted on Twitter in January that the server was open to attack. The coding error that left a database on the server vulnerable was promptly identified and fixed, but the data had already been extracted," university officials said in a statement.

The server did not contain any financial data used for identity theft, such as Social Security numbers, birth dates or credit card numbers, University spokesman Dennis O'Shea told the AP.  Much of the stolen data is employee information that is publicly available from the department website.

"Identity theft does not appear to be a serious issue here," O'Shea  told The Baltimore Sun. "Nevertheless, we felt it was important to notify our students, faculty and staff, and alumni."

School officials said the hackers also tried extorting the university out of server passwords on Wednesday, but the university did not grant the request.

School officials are investigating the breach and cooperating with an FBI criminal probe.

The University is currently pursuing efforts to have the stolen information that was posted removed from the websites where it appears, O'Shea said.