RICHMOND, Va. (AP) - Virginia's attorney general and the top attorneys in other states are investigating whether opioid manufacturers have used unlawful marketing and sales practices.

Attorney General Mark Herring said in a statement on Thursday that the bipartisan group of attorneys general is looking into whether drug manufacturers played a role in creating or prolonging the addiction epidemic.

Herring didn't provide further details about the investigation, including what companies they're investigating. His office couldn't provide a list of all the states involved, but attorneys general in Pennsylvania, Texas and Illinois, among others have said they have joined the investigation.

Herring says in a statement that the investigation into the "culpability of opioid manufacturers in creating, sustaining and extending" the drug crisis is part of an ongoing effort to tackle the problem in Virginia.