(NEXSTAR) – At least 14 people have been arrested in India following a scheme to administer fake COVID-19 vaccines to unsuspecting patients.

The vaccines, which likely contained a saline solution, were reportedly given to thousands at Mumbai-area vaccination centers, or “camps,” officials said earlier this week. The hospital that arranged for the fraudulent vaccinates has also been shut down, the Times of India reports.

“We have arrested doctors,” said Vishal Thakur of the Mumbai police, CNN reported. “They were using a hospital which was producing the fake certificates, vials, syringes.”

Authorities say around 2,500 individuals, but reportedly as many as 4,000, were injected with the fake shots. Many of those paid as much as 1,260 rupees per dose (approximately $17), in cash, directly to organizers.

Police say a housing authority in Kandivali, just outside of Mumbai, had initially reached out to a hospital for help organizing a vaccination site earlier this year. Another hospital altogether — Shivam Hospital — was put in charge of the vaccinations. The hospital had previously administered vaccines in an official capacity, but had lost its license to do so before the scheduled vaccinations at the housing authority, the Times of India reported.

Investigators also believe that the staffers who came up with the scheme had initially intended to provide real vaccines, but ran out of money to do so, according to the Times of India.

The fake vaccinations later occurred at no fewer than nine of 12 vaccination camps, investigators believe. Staffers allegedly went as far as to carry the fake vaccine vials in refrigerated cases, so as not to arouse suspicion.

Residents of the housing complexes later contacted the authorities after the hospital failed to send certification for the vaccinations, triggering their suspicions.

At least 14 people have been arrested in connection with the investigation, including doctors, an event organizer, and the owner of the hospital.