Saudi Arabia summoned on Tuesday the Iranian ambassador over a recent hotel incident that left four of its children dead, and 28 others poisoned in Mash'had. "The Ministry of Foreign Affairs had summoned the ambassador of the Islamic Republic of Iranand expressed its deep concern over the incident and the importance of a swift investigation by Iranian authorities," Saudi news agency SPA quoted Osama Nakly, foreign ministry press chief, as saying. The deaths are believed to have been caused by a chemical leak into the room where the four children were staying, through the central air-conditioning ducts. A family source told the Saudi Gazette on Monday that the family had travelled to Mash'had last Friday. The poisoning occurred 48 hours after they arrived. The children who died are Haidar Ali Qassim, infant Hussein Ali Al-Awwami, Hassan Abulghani Al-Fakhr and a girl Deemah Abdulghani Al-Fakhr. The source confirmed that the father of two of the dead children Abdulghani Al-Fakhr, his wife and son Muhammad are in intensive care. Nakly confirmed that Saudi officials in Iran arrived at the scene immediately after the incident to offer those affected the necessary medical attention. The Saudi embassy in Tehran contacted the Iranian authorities and the foreign ministry soon after and requested an investigation into the circumstances surrounding the tragedy, said Nakly adding that the case was of high importance to the Saudi kingdom. "The Iranian ambassador had been requested to cooperate with the (Saudi) embassy in Tehran as well as the (Saudi) consulate in Mashhad and allow them to monitor the medical condition of those affected," said Nakly. Nakly further emphasized the importance of providing protection to Saudi citizens in Iran. The press secretary offered his condolences to the families of those killed in the incident and said he hoped for a speedy recovery of those hurt in Mashhad. On Monday, Iran's official IRNA news agency quoted Gholam Hossein Mohseni Ejehi, the spokesman for the judiciary, as saying authorities were investigating the incident and that five people had been arrested. "There is no evidence to show the incident was a deliberate act," Ejehi said, without elaborating on the nature of the charges. The five arrested are all employees of the hotel. IRNA said the victims included a 14-year-old girl and three young boys, all age 3. Ejehi said 24 other people were hospitalized after being poisoned. The substance 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 pilgrims each year, coming from Saudi Arabia, Iraq, Bahrain, Azerbaijan and the Indian subcontinent. The Cultural Heritage, Handicrafts and Tourism Organization, a government agency, said in a statement that insect repellant sprayed around the fifth floor of the hotel accidentally leaked into the victims' rooms.