Authorities in Puerto Rico have issued more than 100 arrest warrants for suspects they say ran a multimillion-dollar drug trafficking ring tied to more than 30 killings.

Officials say over 20 people have been arrested as of Thursday morning. Forty-eight of the suspects are in Puerto Rico, 24 on the U.S. mainland and one in the Dominican Republic. The rest are already in prison.

U.S. Attorney Rosa Emilia Rodriguez said the gang aimed to control drug trafficking in the northern city of Bayamon and a spate of killings there nearly two months ago is tied to the group.

Puerto Rico continues to struggle with a surge in homicides. Police say 50 people have been killed so far in January, compared with 34 last year in the same period.