TEHRAN, Iran – Iranian authorities have arrested five people over the deaths of four young Saudi pilgrims in Iran as a result of an accidental mass poisoning in their hotel, Iran’s official IRNA news agency reported Monday.

The report quoted Gholam Hossein Mohseni Ejehi, the spokesman for the judiciary, as saying authorities are investigating the incident. The five people arrested are all employees of the hotel.

“There is no evidence to show the incident was a deliberate act,” Ejehi said, without elaborating on the nature of the charges.

IRNA said the victims included a 14-year-old girl and three young boys, all age 3. Ejehi said 24 other people were hospitalized over exposure to the poison, which is commonly used to kill insects and rats.

The incident took place in the northeastern Iranian city of Mashhad, which is home to a major Shiite Muslim Shrine. The city is visited by nearly two million foreign religious pilgrims per year, coming from Saudi Arabia, Iraq, Bahrain, Azerbaijan and the Indian subcontinent.