The top prosecutors in 21 of Mexico’s 31 states and the federal district have abruptly quit.

There was no immediate explanation Tuesday whether the federal prosecutors are leaving on their own or were forced out. But their departure comes on top of a widespread purge of Mexican prosecutors instituted by Attorney General Marisela Morales at a time when the country faces rampant violence from drug cartels.

Her office said recently that during her first 100 days in office, 462 prosecutors and other officials had been dismissed and another 111 are facing a variety of criminal charges.

In announcing the latest departures, Morales called the purge “fundamental” to giving Mexicans “the results they legitimately demand.” She said public officials must act with “total dedication and responsibility of service.”

The attorney general’s office said, however, that none of the 21 senior prosecutors who quit is under investigation.