NEED TO KNOW

• A family of four died in Istanbul, and while the cause was initially suspected to be food poisoning, it has since been linked to chemical pesticides

• Investigators believe pesticides used in the hotel may have spread through ventilation, causing fatal chemical exposure

• Eleven people, including hotel staff and a pesticide worker, have been arrested as the investigation continues

Authorities are investigating whether chemical poisoning killed a family of four in Turkey.

PEOPLE previously reported that Servet Böcek, 38, his wife Çiğdem, 27, and their two children Kadir, 6, and Masal, 3, died “on suspicion of food poisoning,” while on vacation in Istanbul, the city’s Regional Health Chief, Dr. Abdullah Emre Guner shared on X on Nov. 13.

However, it was then reported that the family — who had been staying in the Fatih district of Istanbul — may have been exposed to pesticides at their accommodation, per CBS News and Metro, who cited Turkish media.

Hürriyet Daily News also reported that two more tourists fell ill at the Harbour Suites Old City, where the family of four also stayed.

Meanwhile, according to a new report by Deutsche Welle, released Wednesday, Nov. 19, phosphine-producing pesticides are being investigated.

It’s also being investigated whether the family was exposed to severe amounts of aluminium phosphide, used in pesticides, The New York Times reported, citing local outlets.

PEOPLE has contacted the Turkish National Police for comment.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Deutsche Welle reported that samples from the bodies of the mother and two children underwent forensic analyses, citing local outlet Cumhuriyet.

It’s believed that bedbug killer products were sprayed in the ground-floor room and that it travelled into the family’s room via the ventilation system, CNN reported, citing local media.

“Primarily, it is believed that they died as a result of chemical poisoning caused by the circumstances in the hotel where they were staying,” the initial report read, per Deutsche Welle.

Officials are still carrying out pathological, microbiological, toxicological and chemical examinations and analyses on the bodies.

Food poisoning is now being considered an unlikely cause of the deaths, per Deutsche Welle.

Eleven people have been arrested, including the Harbour Suites Old City hotel owner, two hotel staff members, a pesticide worker, a mussels vendor and a pita bread seller, per The New York Times, who cited news agency Anadolu.

While four out of the seven are in jail, the rest of those are still being held in detention as prosecutors investigate what charges to file, according toThe New York Times, citing local news agency Demiroren. Official charges have not been released at this time.

Böcek reportedly died on Monday after his wife and two children were confirmed deceased on Nov. 14.

The family had traveled from Hamburg, Germany, to Istanbul on vacation on Nov. 9.

PEOPLE has reached out to the Harbour Suites Old City for comment.

Read the original article on People