The hackers, who are not believed to be connected to the Iranian government, were able to make about $6 million and caused the victims of the scheme to lose more than $30 million, prosecutors said.

Other victims included the cities of Atlanta and Newark, N.J., the Port of San Diego and six health care companies across the U.S., according to the Justice Department.

“SamSam ransomware is a dangerous escalation of cybercrime,” said Craig Carpenito, the U.S. attorney for New Jersey, where Wednesday’s indictment was unsealed. “This is a new type of cybercriminal. Money is not their sole objective. They are seeking to harm our institutions and our critical infrastructure.”

The Justice Department would not say whether any of the municipalities paid the ransom. The Atlanta Journal-Constitution reported in April that Atlanta entered into emergency contracts worth $2.7 million to help restore the city’s computer network after the attack.

The hacking scheme was sophisticated not only because it targeted public institutions but because the hackers targeted the entities after business hours and used European-based servers to launch the remote attacks, Carpenito said.