WASHINGTON (Reuters) — Ninety-one people including doctors, nurses and other medical professionals were charged criminally after an investigation of Medicare fraud that involved $430 million in false billing in seven cities, officials said on Thursday.


It was the government’s second big raid in recent months after a similar investigation in May involving $452 million in possible fraud in Medicare, the health program for the elderly and disabled.


The accusations include billing the government for unnecessary ambulance rides in California, writing prescriptions for patients in Dallas who did not qualify for them and paying kickbacks like food and cigarettes to patients in Houston if they attended programs for which a hospital could bill.


The investigation is part of an effort by the Obama administration to find health care savings.


Indictments against the 91 defendants were unsealed on Thursday after a coordinated investigation led by the departments of justice and of Health and Human Services, officials said. Most of the 91 surrendered or were arrested.


Those charged were trying to make a living by defrauding Medicare and its sibling program, Medicaid, which insures the poor, the officials said.


Of the 91 people charged this week, 33 were involved in false billing in the Miami area. In separate cases, people were accused of improperly billing the government for home health and mental health services.


Officials said they had found an additional $42 million in improper claims at a Houston hospital, Riverside General, where they earlier said they had found $116 million in fraud.


In those cases officials said patients had received cigarettes and other kickbacks if they attended a partial hospitalization program. Some patients watched TV instead of receiving services there, the government said.


Riverside General’s president was among seven employees facing charges on Thursday.


Later on Thursday, a Riverside General clerk read a statement by phone saying the hospital’s board was “saddened as to the tactics utilized against this hospital” but backed its president, Earnest Gibson III. The board was awaiting legal advice and had no further comment, she said.