Fifteen persons, including minors, have been held in Uttar Pradesh’s Ghaziabad for suspected espionage after allegedly filming military sites, railway stations and other sensitive installations, and sharing the photos, videos and location coordinates with foreign handlers, The Indian Express reported on Saturday.

Nine were detained on Friday after six suspects were held on March 14 as part of a probe by a Special Investigation Team. It was unclear how many of those detained were minors.

The investigation team detained the persons on Friday after questioning the suspects who had been held earlier, the newspaper reported. During questioning, eleven names had surfaced, of whom nine were detained.

The adults arrested on Friday have been identified as Ganesh Giri (20), Vivek Rai (18), Gagan Prajapati (22) and Durgesh Nishad (26), the Hindustan Times reported.

Additional Commissioner of Police Raj Karan Nayyar was quoted by the newspaper as saying that two others, Naushad Ali and Sameer Ali, are absconding.

“During the interrogation, it came to light that the suspects were given tasks by their foreign handlers to install solar-powered, SIM-based, standalone CCTV cameras,” Nayyar told the Hindustan Times, adding that the police had recovered two such surveillance cameras.

The two cameras were seized from railway stations in Sonipat, Haryana and Delhi cantonment, The Times of India reported.

Deputy Commissioner of Police (City Zone) Dhawal Jaiswal told the Hindustan Times that the suspects had been operating for six months.

Investigators said that the persons accused in the matter also had a mobile application to share global positioning system, or GPS, coordinates with their handlers. They allegedly shared one-time passwords linked to Indian SIM cards, enabling the handlers to operate accounts using Indian numbers.

“In exchange, they used to get money ranging from Rs 500 to Rs 5,000,” the police alleged.

The police alleged that the SIM cards were either stolen or had been registered in the names of family members. Officers were quoted as having added that the suspects were part of a larger network and that further investigation is underway to identify additional links and locations.

A case has been registered under sections of the Bharatiya Nyaya Sanhita pertaining to endangering the sovereignty and integrity of India and criminal conspiracy, and the Official Secrets Act, The Indian Express reported.